Assessment of the relative tectonic activity of the Longxian–Baoji Fault Zone in the northeastern Tibetan Plateau based on geomorphic indices

Qi Huang,Xiaohu Zhou,Jiyuan You,Shuaishuai Xu,Lushan Liu,Yang Wang 한국지질과학협의회 2023 Geosciences Journal Vol.27 No.6

Since the Late Cenozoic, tectonic deformation has been intense in the Longxian–Baoji Fault Zone (LBFZ), which is at the intersection of the southwest margin of the Ordos Block, the northeast margin of the Tibet Plateau, and the Qinling Orogenic Belt. To evaluate the relative tectonic activity within the LBFZ and discuss the influence of the northeastward expansion of the Tibetan Plateau on the geomorphological evolution of the LBFZ, we extracted data of the Qianhe, Hengshuihe, and Jinlinghe River Basins from the ASTER GDEM and analyzed the geomorphic indices, including the hypsometric integral (HI), standardized stream length-gradient index (SL/K) and Hack profile, elongation ratio (Re), the drainage basin asymmetry factor (AF) and valley floor width-to-height ratio (VF). Through geomorphic indices and field investigations, we found that the LBFZ has experienced relatively high tectonic activity. Combined with the index of relative active tectonics (IAT), we compared the tectonic activity strengths of the four major faults in the study area. Among them, the tectonic activities of the Longxian-Qishan Fault (LQF) and the Taoyuan-Guichuansi Fault (TGF) are the highest. The morphology and AF values of the drainage basin of the southwest side of the study area indicate the influence of northwest-southeast compressive stress. The northeastward expansion of the Tibetan Plateau affected the LBFZ region, and the stress brought about by it controlled the tectonic deformation in the region and sculpted the modern landscape. This study is of great significance for understanding the impact of the northeastward expansion of the Tibetan Plateau on the geomorphological evolution of the LBFZ.

Commutation Torque Ripple Suppression in Three Phase Brushless DC Motor Using Open-end Winding

Qi Huang,Ling Luo,Yuan Zhang,Jichao Cao 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.8

Three phase brushless DC motor has the characteristics of high power density, simple structure and excellent speed regulation performance, which is widely used in the field of electric drive. Open-end winding brushless DC motor has no neutral point, and each phase winding is electrically isolated, which can realize the independent control of each phase winding. Compared with Y-connected brushless DC motor, the open-end winding brushless DC motor has a wider range of speed regulation under the same voltage, and has certain fault-tolerant performance, which is suitable for the application of low voltage and large current. Compared with the multiphase fault-tolerant motor, open-end winding brushless DC motor has simpler structure and higher winding utilization rate. However, the open-end winding brushless DC motor still has torque ripple, among which the cogging torque is related to the motor body structure, while commutation torque ripple is affected by the mutual inductance ofthe winding and the current freewheeling loop. The commutation process of the open-winding brushless DC motor is analyzed, and it is concluded that the current change rates of the turn-off phase and turn-on phase are equal under the ideal back electromotive force(back-EMF), which can ensure that the non-commutation phase current and the electromagnetic torque kept constant. The overlapping commutation with phase current closed-loop method is proposed to suppress the commutation torque ripple of open-end winding BLDC motor, and the applied voltage on turn-off phase and delayed time of turn-off phase in overlapping commutation are derived, the sliding mode observer is used to calculate the electromagnetic torque. MATLAB simulation and experimental results verify the effectiveness of this method.

Design and research of deep slot universal motor for electric power tools

Qi, Huang,Ling, Luo,Jichao, Cao,Wei, Xi The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.6

In this paper, a deep slot universal motor is designed for electric power tools. The deep slot structure can reduce the cost of universal motor materials and improve production efficiency. A mathematical model of a universal motor is established and a simulation model is established by MagNet finite element software. Then, the static magnetic field distribution and load characteristics of the deep slot universal motor are analyzed. Different methods are adopted to improve the commutation spark of a deep slot universal motor. Finally, three 550-W and 9500-rpm prototype motors are tested. Simulation and experimental results indicate that an uneven air gap, brush offset by a certain angle, as well as different turns of the lead coil and the lag coil can effectively improve the commutation spark of a deep slot universal motor.

Finely-reconciled high dielectric constant and low dielectric loss in ternary polymer/Cr2C3/montmorillonite composite films by filler-synergy strategy

Deng Qihuang,Zhou Junquan,Li Xianping,Feng Yefeng,Liang Yurun,Liu Qihang 한국물리학회 2021 Current Applied Physics Vol.22 No.-

Polymer/conductive ceramic composites with high dielectric constant have become research hotspot of dielectric capacitor materials. However, the conductivity and dielectric loss increase when high dielectric constant is achieved. In order to reconcile high dielectric constant and low dielectric loss, in this study, poly (vinylidene fluoride) (PVDF)/chromium carbide (Cr2C3)/montmorillonite (MMT) ternary composite films were prepared by solution cast. Dielectric response based on interfacial polarization was improved and dielectric constant of composites was increased. MMT ceramic was used to suppress interface leakage current. Compared with PVDF/ Cr2C3 composites, the conductivity and dielectric loss of ternary composites were reduced.

Strong and biocompatible poly(lactic acid) membrane enhanced by Ti₃C₂T_z (MXene) nanosheets for Guided bone regeneration

Chen, Ke,Chen, Youhu,Deng, Qihuang,Jeong, Seol-Ha,Jang, Tae-Sik,Du, Shiyu,Kim, Hyoun-Ee,Huang, Qing,Han, Cheol-Min Elsevier 2018 Materials letters Vol.229 No.-

<P><B>Abstract</B></P> <P>Herein, strong and biocompatible Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>z</SUB>-enhanced poly(lactic acid) (PLA) nanocomposite membranes were prepared. The interface of the Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>z</SUB> nanosheets with the hydrophobic PLA matrix was mediated using n-octyltriethoxysilane (OTES). The optimized ultimate tensile strength of the OTES-Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>z</SUB>/PLA nanocomposite membrane was 72 MPa (33% higher than that of a pure PLA membrane). The addition of Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>z</SUB> enhanced the biological properties of the membrane, including the <I>in vitro</I> adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 mouse preosteoblasts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> First effort to introduce MXene into polymer matrix for tissue engineering. </LI> <LI> A robust strategy developed to prepare Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>z</SUB>-enhanced PLA nanocomposite. </LI> <LI> Successful interfacial mediation between hydrophilic Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>z</SUB> nanosheets and hydrophobic PLA. </LI> <LI> Intriguing future of this strong and biocompatible nanocomposite for GBR membrane. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Improving Dielectric Properties in Novel P(VDF‑HFP)/V2AlC MAX/Montmorillonite Composite Films via Interfacial Electric‑Leakage Depressing Strategy

Xiaofeng Xia,Junquan Zhou,Huimin Ding,Qin Li,Maolin Bo,Qihuang Deng,Yefeng Feng 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.1

Dielectric constants of polymer/conductor composites are often high, owing to strong interface interaction in those composites. They can be used for dielectric energy storage, but they usually have high dielectric loss and conductivity. In order toreduce the dielectric loss and conductivity in poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP))/V2AlC MAXcomposites, in this study, we explored the novel P(VDF-HFP)/V2AlC MAX/montmorillonite (MMT) ternary composites. Compared with binary composites, the ternary composites showed the mildly reduced dielectric constant, significantlydecreased dielectric loss and conductivity. Using highly-conductive V2AlCMAX filler aimed at taking advantage of thepolymer/MAX interface polarization to increase the dielectric response of composites. Employing well-insulating MMTfiller aimed at reducing the interface electric leakage conduction. At 1 kHz, the outstanding ternary composite with 2 wt%MMT and 20 wt% MAX could exhibit a high dielectric constant of ca. 27 and low dielectric loss of ca. 0.21. This workmight offer a new research idea for the construction of high-performance composite dielectric films containing modernMAX ceramic fillers.

Realizing Rationally-Balanced Dielectric Properties in Fluoropolymer/Cr2AlC MAX Composites Modified by 2D-BN

Qin Li,Junquan Zhou,Yanhui Chen,Xiaofeng Xia,Maolin Bo,Qihuang Deng,Yefeng Feng 한국고분자학회 2020 Macromolecular Research Vol.28 No.13

Polymer/conductor composite dielectric materials have a high dielectric constant. In recent years, composite dielectrics have become a study hotspot in highdensity energy storage capacitors. However, high dielectric loss and high electrical conductivity make the application of the composite materials very limited. In order to obtain composite materials with high dielectric constant, low dielectric loss and low conductivity, we added the insulating boron nitride (BN) filler into polymer/Cr2AlC composites. As a conductive filler, Cr2AlC ternary-layered-compound (MAX) ceramic has an interface polarization with the polymer matrix, thereby increasing the dielectric constant of the composites. The insulating BN has a very low electrical conductivity, which can effectively reduce the electrical conductivity and dielectric loss of the composites. Compared with the binary polymer/Cr2AlC composite materials, the ternary polymer/Cr2AlC/BN composite materials can achieve the low dielectric loss and low conductivity as well as properly-lowered dielectric constant. The ternary composite material filled with 10 wt% Cr2AlC and 2 wt% BN has a dielectric constant of about 30, a dielectric loss of about 0.7 and a conductivity of about 4.6×10- 7 S m-1 at 100 Hz. In this work, high-performance composite dielectrics were prepared through good cooperation between conductive and insulating ceramic fillers, which might provide an idea for design of promising energy storage capacitors.

Lowering Dielectric Loss and AC Conductivity of Polymer/HfC Composite Dielectric Films via Insulating Montmorillonite Barrier

Peiyao Chen,Binghe Chen,Ben Qin,Jiangqiong Wang,Qihuang Deng,Yefeng Feng 한국고분자학회 2021 Macromolecular Research Vol.29 No.9

Present work aimed at studying the effect of montmorillonite (MMT) on dielectric and conductive properties of composites based on polymer/hafnium carbide (HfC) mother composite system. Polymer/HfC/MMT composite films based on double-filler modification strategy were prepared by solution cast. To obtain control group, binary polymer/HfC composite films were prepared. MMT ceramic had excellent insulation property, which could suppress interface leakage current and thus reduce dielectric loss of composites. Compared with binary system, ternary system could show better overall electric features including mildly reduced permittivity, obviously reduced dielectric loss and conductivity. Optimized ternary composite bearing 3 wt% HfC and 3 wt% MMT exhibited a high permittivity of 34, low dielectric loss of 0.33 and low conductivity of 5.5 × 10-7 S m-1 at 100 Hz. This research might enable the fabrication of advanced composite dielectrics.

UTX regulates mesoderm differentiation of embryonic stem cells independent of H3K27 demethylase activity

Wang, Chaochen,Lee, Ji-Eun,Cho, Young-Wook,Xiao, Ying,Jin, Qihuang,Liu, Chengyu,Ge, Kai Proceedings of the National Academy of Sciences 2012 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.109 No.38

<P>To investigate the role of histone H3K27 demethylase UTX in embryonic stem (ES) cell differentiation, we have generated <I>UTX</I> knockout (KO) and enzyme-dead knock-in male ES cells. Deletion of the X-chromosome-encoded <I>UTX</I> gene in male ES cells markedly decreases expression of the paralogous <I>UTY</I> gene encoded by Y chromosome, but has no effect on global H3K27me3 level, <I>Hox</I> gene expression, or ES cell self-renewal. However, <I>UTX</I> KO cells show severe defects in mesoderm differentiation and induction of <I>Brachyury</I>, a transcription factor essential for mesoderm development. Surprisingly, UTX regulates mesoderm differentiation and <I>Brachyury</I> expression independent of its enzymatic activity. UTY, which lacks detectable demethylase activity, compensates for the loss of UTX in regulating <I>Brachyury</I> expression. UTX and UTY bind directly to <I>Brachyury</I> promoter and are required for Wnt/β-catenin signaling-induced <I>Brachyury</I> expression in ES cells. Interestingly, male <I>UTX</I> KO embryos express normal levels of <I>UTY</I> and survive until birth. In contrast, female <I>UTX</I> KO mice, which lack the <I>UTY</I> gene, show embryonic lethality before embryonic day 11.5. Female <I>UTX</I> KO embryos show severe defects in both <I>Brachyury</I> expression and embryonic development of mesoderm-derived posterior notochord, cardiac, and hematopoietic tissues. These results indicate that UTX controls mesoderm differentiation and <I>Brachyury</I> expression independent of H3K27 demethylase activity, and suggest that UTX and UTY are functionally redundant in ES cell differentiation and early embryonic development.</P>

Ni Nanoparticle Anchored on MWCNT as a Novel Electrochemical Sensor for Detection of Phenol

Yajing Wang,Jiankang Wang,Zhongping Yao,Chenyu Liu,Taiping Xie,Qihuang Deng,Zhaohua Jiang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.11

Increasing active sites and enhancing electric conductivity are critical factors to improve sensing performance toward phenol. Herein, Ni nanoparticle was successfully anchored on acidified multiwalled carbon nanotube (a-MWCNT) surface by electroless plating technique to avoid Ni nanoparticle agglomeration and guarantee high conductivity. The crystal structure, phase composition and surface morphology were characterized by XRD, SEM and TEM measurement. The as-prepared Ni/a-MWCNT nanohybrid was immobilized onto glassy carbon electrode (GCE) surface for constructing phenol sensor. The phenol sensing performance indicated that Ni/a-MWCNT/GCE exhibited an amazing detection performance with rapid response time of 4s, a relatively wide detection range from 0.01 mM to 0.48 mM, a detection limit of 7.07 μM and high sensitivity of 566.2 μAmM -1 cm -2. The superior selectivity, reproducibility, stability and applicability in real sample of Ni/a-MWCNT/GCE endowed it with potential application in discharged wastewater.