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An ultrasonic multi-wave focusing and imaging method for linear phased arrays

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Chinese Physics B 2021年第7期30卷 303-310页

作者： yu-xiang dai Shou-Guo Yan Bi-Xing Zhang Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100190China

To overcome the inherent limits of traditional single wave imaging for nondestructive testing,the multi-wave focusing and imaging method is thoroughly *** method makes the compressional waves and shear waves focused in both emission and reception processes,which strengthens the focusing energy and improves the signal-to-noise ratio of received signals.A numerical model is developed to study the characteristics of a multi-wave focusing *** is shown that the element width approaching 0.8 wavelengths of shear waves can keep a balance between the radiation energy of two waves,which can achieve a desirable multi-wave focusing *** an experiment using different imaging methods for a linear phased array is *** can be concluded that due to the combination of the propagation and reflection characteristics of two waves,the multi-wave focusing and imaging method can significantly improve the imaging distinguishability of defects and expand the available sweeping range to a sector of-650 to 65°.

关键词： multi-wave focusing ultrasonic imaging phased array non-destructive testing

Ultrasonic beam focusing characteristics of shear-vertical waves for contact-type linear phased array in solid

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Chinese Physics B 2020年第3期29卷 270-276页

We investigate the beam focusing technology of shear-vertical(SV) waves for a contact-type linear phased array to overcome the shortcomings of conventional wedge transducer arrays. The numerical simulation reveals the transient excitation and propagation characteristics of SV waves. It is found that the element size plays an important role in determining the transient radiation directivity of SV waves. The transient beam focusing characteristics of SV waves for various array parameters are deeply studied. It is particularly interesting to see that smaller element width will provide the focused beam of SV waves with higher quality, while larger element width may result in erratic fluctuation of focusing energy around the focal point. There exists a specific range of inter-element spacing for optimum focusing performance. Moreover, good beam focusing performance of SV waves can be achieved only at high steering angles.

关键词： beam focusing shear-vertical(SV)waves contact-type linear phased array solid

Regulation of electronic structure of monolayer MoS_(2) by pressure

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Rare Metals 2022年第5期41卷 1761-1770页

作者： Qiao-Lu Lin Zheng-Fang Qian xiang-yu dai Yi-Ling Sun Ren-Heng Wang Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China

Understanding pressure-regulated electronic properties is crucial for integrating two-dimensional semiconductors into flexible electronic devices and pressure sensors. We thoroughly explored the tunability of the electronic structure of monolayer MoS_(2) upon the application of perpendicular pressure and shear stress by using first-principles calculations. The band gap increased at low pressures and then decreased as the pressure *** in the band gap are caused by the combined interaction of the increasing and decreasing trends in the band gap. The increase in the band gap is induced by the enhancement of the p–d orbital interaction at the top of the valence band(TVB). The delocalization of charge and unstable hybridization bonding causes a reduction in the band gap. The band gap under perpendicular pressure modes is closely related to the structural variation. Shear stress can effectively reduce the band gap with minimal change to the crystal structure. The maximum point at the TVB and the minimum point at the bottom of the conduction band are different for all pressure modes, resulting in various anisotropic properties. This study provides a theoretical basis for modulating the electrical and optical properties of monolayer MoS_(2).

关键词： Band gap Pressure Monolayer MoS_(2) Electronic structure Shear stress

A new sequential two-stent strategy for treating true distal left main trifurcation lesion

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Journal of Geriatric Cardiology 2021年第6期18卷 487-491页

作者： yu-xiang dai Chen-Guang LI Jia HUANG Ren-De XU Shu-Fu CHANG Hao LU Dao-yuan REN Lei GE Ju-Ying QIAN Feng ZHANG Jun-Bo GE Department of Cardiology Zhongshan HospitalFudan UniversityShanghai Institute of Cardiovascular DiseasesShanghaiChina

The incidence of significant left main(LM)coronary artery stenosis identified by coronary angiography was 5%−17.5%in various clinical presentations;about 80%of stenosis involved the LM bifurcation(LMB).[1]Although per-cutaneous coronary intervention(PCI)is an appro-priate alternative to coronary artery bypass graft in LM disease with low-to-intermediate anatomical complexity,[2]PCI for LMB lesions remains the most technically challenging for interventional cardiolo-gists with higher rates of acute periprocedural com-plications and higher risk of long-term major ad-verse cardiac events in the era of drug-eluting stent(DES).

关键词： stenosis acute bypass

Observation of acoustic hybrid topological phases induced by the p-d orbital interactions

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 132-139页

作者： Xiao xiang Feng Gao yu-Gui Peng Peng Wu Zong-Lin Li Xue-Feng Zhu School of Physics and Innovation Institute Huazhong University of Science and Technology

In spinless systems,growing attention has recently been attracted to synthetic gauge fields,which redefine the fundamental crystal symmetries by utilizing the projective algebraic ***,synthetic gauge fields have been commonly investigated in single orbital systems,and explorations on hybrid orbitals remain elusive in ***,we report the experimental observation of hybrid topological phases induced by hybrid synthetic gauge flux,which is formed by the interaction between p and d orbitals embedded in acoustic *** breaking the translation symmetries of Lxand/or Ly,we unambiguously demonstrate the first-order M?bius edge states and higher-order corner *** work establishes a platform for seeking exotic topological phases induced by hybrid-orbitals interactions and initializing the framework of hybrid-orbitalsrelated topological *** applications can be anticipated in scenarios such as high-quality sensing and robust wave trapping due to the stepwise energy distribution of the hybrid topological phase.

关键词： topological insulator synthetic gauge field projective symmetry corner states

γ射线暴的最新研究进展:火球模型、余辉及前身星

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物理学进展 2002年第2期22卷 131-162页

作者：王祥玉戴子高陆埮南京大学天文系南京210093

γ射线暴 (称简γ暴 )的研究在最近几年里有了巨大的突破。观测上 ,人们发现了γ暴的低能余辉以及与γ射线爆发同时的光学爆发 ,还发现了它位于宇宙学距离的寄主星系。越来越多的观测证据还表明长时标γ暴与恒星形成区、甚至可能与超新... 详细信息

γ射线暴 (称简γ暴 )的研究在最近几年里有了巨大的突破。观测上 ,人们发现了γ暴的低能余辉以及与γ射线爆发同时的光学爆发 ,还发现了它位于宇宙学距离的寄主星系。越来越多的观测证据还表明长时标γ暴与恒星形成区、甚至可能与超新星成协。在γ暴的相对论火球模型框架下 ,人们对γ暴以及余辉的产生机制的认识也有了进展。进而人们对γ暴的前身星以及环境效应等有了新的认识。

关键词：火球模型余辉 γ射线暴超新星辐射机制产生机制环境效应恒星

Laparoscopic liver resection utilizing the ventral avascular area of the inferior vena cava:A retrospective cohort study

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World Journal of Gastroenterology 2025年第1期31卷 42-57页

作者： Kun Huang Zhu Chen Heng Xiao Hai-Yang Hu Xing-yu Chen Cheng-You Du xiang Lan Department of Hepatobiliary Surgery The First Affiliated Hospital of Chongqing Medical UniversityChongqing 400000China Department of General Surgery Mianyang Hospital of Traditional Chinese MedicineMianyang 621000Sichuan ProvinceChina

BACKGROUND Laparoscopic liver resection(LLR)can be challenging due to the difficulty of establishing a retrohepatic tunnel under *** the third hepatic hilum before parenchymal transection often leads to significant liver mobilization,tumor compression,and bleeding from the short hepatic veins(SHVs).This study introduces a novel technique utilizing the ventral avascular area of the inferior vena cava(IVC),allowing SHVs to be addressed after parenchymal transection,thereby reducing surgical complexity and improving outcomes in in situ *** To introduce and evaluate a novel LLR technique using the ventral avascular area of the IVC and compare its short-term outcomes with conventional *** The clinical cohort data of patients with pathologically confirmed hepatocellular carcinoma or intrahepatic cholangiocarcinoma who underwent conventional LLR and novel LLR between July 2021 and July 2023 at the First Affiliated Hospital of Chongqing Medical University were retrospectively *** novel LLR,we initially separated the caudate lobe from the IVC using dissecting forceps along the ventral avascular area of the ***,we transected the parenchyma of the left and right caudate lobes from the caudal side to the cephalic side using the avascular area as a ***,we addressed the SHVs and finally dissected the root of the right hepatic vein or left hepatic *** short-term postoperative outcomes and oncological results of the two approaches were evaluated and *** A total of 256 patients were included,with 150(58.59%)undergoing conventional LLR and 106(41.41%)undergoing novel *** novel technique resulted in significantly larger tumor resections(6.47±2.96 cm vs 4.01±2.33 cm,P<0.001),shorter operative times(199.57±60.37 minutes vs 262.33±83.90 minutes,P<0.001),less intraoperative blood loss(206.92±37.09 mL vs 363.34±131.27 mL,P<0.001),and greater resection volume(345.11±31.40 mL vs 264.38±31.98 mL,P<0.001)comp

关键词： Laparoscopic liver resection Inferior vena cava Retrohepatic tunnel Short hepatic veins Complex liver tumors Intraoperative bleeding control

Ultralight and superelastic MXene/reduced graphene oxide aerogels for electromagnetic interference shielding

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Nano Research 2025年第1期18卷 1-9页

作者： Xinfeng Zhou Yang dai Guoyao yue Yiman Zhang Lulu Li Zhong-Zhen yu Peng Min Hao-Bin Zhang 21 State Key Laboratory of Organic-Inorganic Composites College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China Beijing Key Laboratory of Advanced Functional Polymer Composites College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China Present address:BOE Technology Innovation Center BOE Technology Group Co.Ltd.Beijing 100176China Xi’an Modern Chemistry Research Institute Xi’an 710065China

Lightweight aerogels feature multifunctionality and a high porosity,yet accompanied with poor structure recovery under large strain *** this work,we develop an air bubble-ice crystal dual template and annealing strategy to integrate low density and high resilience for the conductive transition metal carbides/nitrides(MXene)composite *** air bubbles and ice crystals synergistically exclude the nanosheets to the gas-liquid interfaces,thereby constructing unique Y-shaped junctions and robust *** annealing process greatly enhances the interlayer *** external load,the Yshaped structures prevent the stress concentration at the junctions by transferring the forces to the skeleton for maintaining structural *** addition,the wrinkled and thick cell walls,together with the enhanced interlayer interactions,endow the aerogel with exceptional structural stability and *** a result,the MXene/reduced graphene oxide(RGO)composite aerogels exhibit superelasticity with reversible compressive strains of up to 95%.In addition,the electron bridging effect of the RGO sheets affords the aerogel to deliver excellent electromagnetic interference shielding performance,as high as 46.3 dB at 2.5 ***,the remarkable reshapeability of the aerogels allows for precise regulation of structure and performance(33.5-75.1 dB)by a simple wetting compression *** summary,this work offers helpful inspirations for developing lightweight and superelasticity aerogels for extensive applications.

关键词： lightweight superelasticity MXene aerogel electromagnetic interference shielding reshapeability

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羧甲基玉米淀粉合成工艺的改进

四川大学学报（工程科学版） 2003年第1期35卷 115-118页

作者：胡湘渝刘代俊四川大学化学工程学院四川成都610065

以玉米淀粉为原料,采用改进的合成方法,即对反应物料进行碱前处理,并加入促进剂,制备了羧甲基玉米淀粉钠。以取代度为目标,研究了氢氧化钠、反应时间、反应温度等因素对反应的影响,以及取代度与产品物性的关系,确定了优化的工艺参数为:... 详细信息

以玉米淀粉为原料,采用改进的合成方法,即对反应物料进行碱前处理,并加入促进剂,制备了羧甲基玉米淀粉钠。以取代度为目标,研究了氢氧化钠、反应时间、反应温度等因素对反应的影响,以及取代度与产品物性的关系,确定了优化的工艺参数为:氢氧化钠∶一氯乙酸=2∶1(摩尔比),反应温度60℃,反应时间120min,淀粉15g,促进剂22g。

关键词：合成工艺玉米淀粉羧甲基淀粉取代度工艺参数工艺改进