Thermal Management Performance of Epoxy Composites with Boron Nitride and Boron Phosphide Hybrid Fillers

Yi Wang,Kai Wang,Jiajun Hu,Kang Si,Hongyan Xia 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.6

Thermal interface materials with high thermal conductivity are the best choice to solve the current overheating problem of electronic devices, and the choice of thermal conductive fi ller is a key factor aff ecting the performance of thermal interface composites. Hexagonal boron nitride sheet is considered to be ideal thermal conductive fi ller, but the thermal conductive eff ect of single fi ller is still insuffi cient to meet actual needs. Here, a new type of hybrid fi ller mixed with boron nitride sheet and boron phosphide particles is used to prepare epoxy based composites. When the fi ller volume fraction is 40%, the thermal conductivity of composites reaches 3.18 W m −1 K −1 . Under the same content, the thermal conductivity of the composites with mixed fi llers outperforms those with boron nitride sheet alone. At the same time, the composite material shows high breakdown strength of 46 kV mm −1 . This work provides a new way to prepare thermal interface materials with high thermal conductivity for modern electronic packaging.

Preliminary Application of High-Definition CT Gemstone Spectral Imaging in Hand and Foot Tendons

Kai Deng,Cheng-Qi Zhang,Wei Li,Jun-Jun Wang,Xin-Yi Wang,Tao Pang,Guang-Li Wang,Cheng Liu 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.6

Objective: To assess the feasibility of visualizing hand and foot tendon anatomy and disorders by Gemstone Spectral Imaging (GSI) high-definition CT (HDCT). Materials and Methods: Thirty-five patients who suffered from hand or foot pain were scanned with GSI mode HDCT and MRI. Spectrum analysis was used to select the monochromatic images that provide the optimal contrast-to-noise ratio (CNR) for tendons. The image quality at the best selected monochromatic level and the conventional polychromatic images were compared. Tendon anatomy and disease were also analyzed at GSI and MRI. Results: The monochromatic images at about 65 keV (mean 65.09 ± 2.98) provided the optimal CNR for hand and foot tendons. The image quality at the optimal selected monochromatic level was superior to conventional polychromatic images (p = 0.005, p < 0.05). GSI was useful in visualizing hand and foot tendon anatomy and disorders. There were no statistical differences between GSI and MRI with regard to tendon thickening (χ2 = 0, p > 0.05), compression (χ2 = 0.5, p > 0.05), absence (χ2 = 0, p > 0.05) and rupture (χ2 = 0, p > 0.05). GSI was significantly less sensitive than MRI in displaying tendon adhesion (χ2 = 4.17, p < 0.05), degeneration (χ2 = 4.17, p < 0.05), and tendinous sheath disease (χ2 = 10.08, p < 0.05). Conclusion: GSI with monochromatic images at 65 keV displays clearly the most hand and foot tendon anatomy and disorders with image quality improved, as compared with conventional polychromatic images. It may be used solely or combined with MRI in clinical work, depending on individual patient disease condition. Objective: To assess the feasibility of visualizing hand and foot tendon anatomy and disorders by Gemstone Spectral Imaging (GSI) high-definition CT (HDCT). Materials and Methods: Thirty-five patients who suffered from hand or foot pain were scanned with GSI mode HDCT and MRI. Spectrum analysis was used to select the monochromatic images that provide the optimal contrast-to-noise ratio (CNR) for tendons. The image quality at the best selected monochromatic level and the conventional polychromatic images were compared. Tendon anatomy and disease were also analyzed at GSI and MRI. Results: The monochromatic images at about 65 keV (mean 65.09 ± 2.98) provided the optimal CNR for hand and foot tendons. The image quality at the optimal selected monochromatic level was superior to conventional polychromatic images (p = 0.005, p < 0.05). GSI was useful in visualizing hand and foot tendon anatomy and disorders. There were no statistical differences between GSI and MRI with regard to tendon thickening (χ2 = 0, p > 0.05), compression (χ2 = 0.5, p > 0.05), absence (χ2 = 0, p > 0.05) and rupture (χ2 = 0, p > 0.05). GSI was significantly less sensitive than MRI in displaying tendon adhesion (χ2 = 4.17, p < 0.05), degeneration (χ2 = 4.17, p < 0.05), and tendinous sheath disease (χ2 = 10.08, p < 0.05). Conclusion: GSI with monochromatic images at 65 keV displays clearly the most hand and foot tendon anatomy and disorders with image quality improved, as compared with conventional polychromatic images. It may be used solely or combined with MRI in clinical work, depending on individual patient disease condition.

Micro-scale PLA Fibrous Membranes for Adsorption of Cigarette Smoke

Yi-qing Gu,Zhe Wang,Ying Sun,Yi-Kai Wang,Zhi-juan Pan 한국섬유공학회 2018 Fibers and polymers Vol.19 No.3

Porous PLA fibrous membranes with different morphologies were successfully fabricated by varying the relative humidity. When the relative humidity was higher than 45 %, nanopores morphology appeared on the surface of PLA fibers. The micro-structures of PLA fibers and the packing densities and through-pore sizes of the PLA fibrous membranes were measured and found to greatly influence the smoke adsorption properties. The smoke adsorption was recorded in photos, and the process of how smoke adsorbed on the membranes was observed by SEM. The max removal efficiencies of nicotine, tar, water vapor, and carbon monoxide were 40.0 %, 36.9 %, 5.8 % and 13.6 % measured by a cigarette-smoking machine, and sensory evaluation was conducted to assess the practical application of fibrous membranes for smoke adsorption.

The Influence of Reconstruction Algorithm and Heart Rate on Coronary Artery Image Quality and Stenosis Detection at 64-Detector Cardiac CT

Yi-Ting Wang,Chung-Yi Yang,Jong-Kai Hsiao,Hon-Man Liu,Wen-Jen Lee,Yun Shen 대한영상의학회 2009 Korean Journal of Radiology Vol.10 No.3

Objective: We wanted to evaluate the impact of two reconstruction algorithms (halfscan and multisector) on the image quality and the accuracy of measuring the severity of coronary stenoses by using a pulsating cardiac phantom with different heart rates (HRs). Materials and Methods: Simulated coronary arteries with different stenotic severities (25, 50, 75%) and different luminal diameters (3, 4, 5 mm) were scanned with a fixed pitch of 0.16 and a 0.35 second gantry rotation time on a 64-slice multidetector CT. Both reconstruction algorithms (halfscan and multisector) were applied to HRs of 40-120 beats per minute (bpm) at 10 bpm intervals. Three experienced radiologists visually assessed the image quality and they manually measured the stenotic severity. Results: Fewer measurement errors occurred with multisector reconstruction (p = 0.05), a slower HR (p < 0.001) and a larger luminal diameter (p = 0.014); measurement errors were not related with the observers or the stenotic severity. There was no significant difference in measurements as for the reconstruction algorithms below an HR of 70 bpm. More nonassessable segments were visualized with halfscan reconstruction (p = 0.004) and higher HRs (p < 0.001). Halfscan reconstruction had better quality scores when the HR was below 60 bpm, while multisector reconstruction had better quality scores when the HR was above 90 bpm. For the HRs between 60 and 90 bpm, both reconstruction modes had similar quality scores. With excluding the nonassessable segments, both reconstruction algorithms achieved a similar mean measured stenotic severity and similar standard deviations. Conclusion: At a higher HR (above 90 bpm), multisector reconstruction had better temporal resolution, fewer nonassessable segments, better quality scores and better accuracy of measuring the stenotic severity in this phantom study. Objective: We wanted to evaluate the impact of two reconstruction algorithms (halfscan and multisector) on the image quality and the accuracy of measuring the severity of coronary stenoses by using a pulsating cardiac phantom with different heart rates (HRs). Materials and Methods: Simulated coronary arteries with different stenotic severities (25, 50, 75%) and different luminal diameters (3, 4, 5 mm) were scanned with a fixed pitch of 0.16 and a 0.35 second gantry rotation time on a 64-slice multidetector CT. Both reconstruction algorithms (halfscan and multisector) were applied to HRs of 40-120 beats per minute (bpm) at 10 bpm intervals. Three experienced radiologists visually assessed the image quality and they manually measured the stenotic severity. Results: Fewer measurement errors occurred with multisector reconstruction (p = 0.05), a slower HR (p < 0.001) and a larger luminal diameter (p = 0.014); measurement errors were not related with the observers or the stenotic severity. There was no significant difference in measurements as for the reconstruction algorithms below an HR of 70 bpm. More nonassessable segments were visualized with halfscan reconstruction (p = 0.004) and higher HRs (p < 0.001). Halfscan reconstruction had better quality scores when the HR was below 60 bpm, while multisector reconstruction had better quality scores when the HR was above 90 bpm. For the HRs between 60 and 90 bpm, both reconstruction modes had similar quality scores. With excluding the nonassessable segments, both reconstruction algorithms achieved a similar mean measured stenotic severity and similar standard deviations. Conclusion: At a higher HR (above 90 bpm), multisector reconstruction had better temporal resolution, fewer nonassessable segments, better quality scores and better accuracy of measuring the stenotic severity in this phantom study.

Novel AgCl/Ag2SO3 Hybrids as a Visible-Light-driven Photocatalyst: Preparation, Characterization, and Degradation of Rhodamine-B and Methyl Orange

Xiang-Feng Wu,Yi-Jin Wang,Zuo-Lin Cao,Yan-Mei Feng,Hui Li,Chen-Xu Zhang,Jun-Zhang Su,Jia-Rui Zhang,Yi-Wei Wang,Kai-Yuan Wang,Guo-Wen Sun 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.7

The novel AgCl/Ag2SO3 hybrids as an efficient photocatalyst had been fabricated by an in situ synthetic method. The correlations between the structure and the photocatalytic properties of the as-fabricated hybrids were analyzed. Experimental results exhibited that with increasing the amount of Ag2SO3, the degradation rate of the as-obtained samples was firstly increased and then decreased under the visible light irradiation. When the mass ratio of AgCl to Ag2SO3 was 1:2, in 30?min, it displayed the highest degradation rate of 99.2% for rhodamine-B, which was obviously higher than 46.1, 60.5, and 14.6% of pure AgCl, Ag2SO3, and TiO2 (P25), respectively. Similar results could be found in degradation of methyl orange. It had the maximum of 97.4% in 90?min, which was higher than 55.2, 48.7, and 12.7% of pure AgCl, Ag2SO3, and P25, respectively. Moreover, the as-prepared hybrids possessed the enhanced separation and transfer of photo-generated electron?hole pairs compared to the pure samples. In addition, the holes and superoxide radicals played the dominant role and the hydroxyl radicals played the secondary role during the process of photocatalytic degradation.

Douglas-Peucker-Based Accelerated Similarity Measures for Massive AIS Trajectories

Kai WANG,Ryan Wen LIU,Yan LI,Maohan LIANG,Yi LIU,Jianhua WU,Jingxian LIU 국제이네비해양경제학회 2017 International Journal of e-Navigation and Maritime Vol.8 No.1

With the rapid development of the global economy, transport safety and security have become the key issues in maritime transportation all over the world. In practical applications, the Automatic Identification System (AIS)-based measurement of similarities between different vessel trajectories plays an important role in improving maritime transportation, e.g., maritime navigation, maritime supervision and management. However, the received AIS datasets are usually composed of a large amount of redundant information which could significantly increase the computational complexity. To deal with this problem, a Douglas-Peucker (DP)-based calculation method is introduced in this paper to accurately compress the spatio-temporal AIS trajectories while preserving the main geometrical structures. Based on the compressed trajectories, it is able to accelerate the Dynamic Time Warping (DTW) algorithm for the measurement of similarities between different vessel trajectories. In particular, the combination of DP and DTW has the capacity of significantly reducing the computational cost and guaranteeing the accuracy of similarity measures. The experimental results have demonstrated the superior performance of the proposed method in terms of computational cost and accuracy of similarity measures.

Electron Heating and Current Scaling in a Two-dimensional Electron System in Close Proximity to Nanoscale Scatterers

Yi-Ting Wang,Chun-Kai Yang,Sheng-Di Lin,Chi-Te Liang 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.10

We have performed magneto-transport measurements on a two-dimensional electron system(2DES) which is in close proximity to nanoscaled scatterers. Weak localization, as evidenced bynegative magnetoresistance, is observed. In this work, we use the extracted phase coherence rateas a thermometer to measure the electron’s effective temperature Te in our 2DES when a highdriving current I flows through the device. We find that Te / I0.52, consistent with 1/ep T2in two dimensions, where 1/ep is the electron-phonon scattering rate. However, the phase coherencerate 1/ T, with a very small offset, is consistent with zero-temperature dephasing. Mostimportantly, our experimental results are in agreement with the fact that at low temperatures, thedominant phase-breaking mechanism is electron-electron scattering, not electron-phonon scattering. Therefore we are able to investigate both electron-electron scattering and electron-phonon scatteringwhich are, in most cases, difficult to study independently in the linear region. Our data showthat the electron heating effect is a very powerful tool for studying semiconductor devices.

Research on a Multi-Objective Control Strategy for Current-source PWM Rectifiers under Unbalanced and Harmonic Grid Voltage Conditions

Yi-Wen Geng,Hai-Wei Liu,Ren-Xiong Deng,Fang-Fang Tian,Hao-Feng Bai,Kai Wang 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

Unbalanced and distorted grid voltages cause the grid side current of a current source PWM rectifier to be heavily distorted. They can also cause the DC-link current to fluctuate with a huge amplitude. In order to enhance the performance of a current-source PWM rectifier under unbalanced and harmonic grid voltage conditions, a mathematical model of a current-source PWM rectifier is established and a flexible multi-objective control strategy is proposed to control the DC-link current and grid-current. The fundamental positive/negative sequence, 5th and 7th order harmonic components of the grid voltage are first separated with the proposed control strategy. The grid current reference are optimized based on three objectives: 1) sinusoidal and symmetrical grid current, 2) sinusoidal grid current and elimination of the DC-current 2nd order fluctuations, and 3) elimination of the DC-current 2nd and 6th order fluctuations. To avoid separation of the grid current components, a multi-frequency proportional-resonant controller is applied to control the fundamental positive/negative sequence, 5th and 7th order harmonic current. Finally, experimental results verify the effectiveness of proposed control strategy.

Tazarotene-Induced Gene 1 Interacts with DNAJC8 and Regulates Glycolysis in Cervical Cancer Cells

Wang, Chun-Hua,Shyu, Rong-Yaun,Wu, Chang-Chieh,Chen, Mao-Liang,Lee, Ming-Cheng,Lin, Yi-Yin,Wang, Lu-Kai,Jiang, Shun-Yuan,Tsai, Fu-Ming Korean Society for Molecular and Cellular Biology 2018 Molecules and cells Vol.41 No.6

The tazarotene-induced gene 1 (TIG1) protein is a retinoidinducible growth regulator and is considered a tumor suppressor. Here, we show that DnaJ heat shock protein family member C8 (DNAJC8) is a TIG1 target that regulates glycolysis. Ectopic DNAJC8 expression induced the translocation of pyruvate kinase M2 (PKM2) into the nucleus, subsequently inducing glucose transporter 1 (GLUT1) expression to promote glucose uptake. Silencing either DNAJC8 or PKM2 alleviated the upregulation of GLUT1 expression and glucose uptake induced by ectopic DNAJC8 expression. TIG1 interacted with DNAJC8 in the cytosol, and this interaction completely blocked DNAJC8-mediated PKM2 translocation and inhibited glucose uptake. Furthermore, increased glycose uptake was observed in cells in which TIG1 was silenced. In conclusion, TIG1 acts as a pivotal repressor of DNAJC8 to enhance glucose uptake by partially regulating PKM2 translocation.

Voltage Distortion Suppression for Off-grid Inverters with an Improved Load Current Feedforward Control

Yi-Wen Geng,Xue Zhang,Xiaoqiang Li,Kai Wang,Xibo Yuan 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3

The output voltage of an off-grid inverter is influenced by load current, and the voltage harmonics especially the 5th and 7th are increased with nonlinear loads. In this paper, to attenuate the output voltage harmonics of off-grid inverters with nonlinear loads nearby, a load current feedforward is proposed. It is introduced to a voltage control loop based on the Positive and Negative Sequence Harmonic Regulator (PNSHR) compensation to modify the output impedance at selective frequencies. The parameters of the PNSHR are revised with the output impedance of the off-grid inverter, which minimizes the output impedance of the off-grid inverter. Experimental results verify the proposed method, showing that the output voltage harmonics caused by nonlinear loads can be effectively suppressed.