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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

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

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

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

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

Preparation of bio-beads and Their Atrazine Degradation Characteristics

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Chemical Research in Chinese Universities 2011年第3期27卷 407-412页

作者： bi Hai-tao zhang Lan-ying LIU Na ZHU Bo-lin College of Environment and Resources Jilin University Changchun 130026 P. R. China

Screened atrazine-mineralizing bacterium―Pseudomonas W4 was embedded inside an improved PVA- H3BO3 embedment matrix to make bio-beads to degrade atrazine. The atrazine degradation characteristics were studied. The preparation procedure of bio-beads was as follows：（1） preparing a mixture of 100, 12.5, 10, 1.5 and 1 g/L PVA, bentonite（Ca）, activated carbon powder, sodium alginate and centrifuged Pseudomonas W4 bacterium, respectively; （2） the mixture was dropped into a gently stirred cross linker solution（pH=6.7） and cured at 10 °C for 24 h. The optimal atrazine degradation conditions by bio-beads were as follows： pH=7, the auxiliary carbon source was glucose, and the concentration of glucose was greater than 325 mg/L. The bio-beads demonstrated stronger tolerance ability than the free microorganism to the increase of PCBs, hydrogen ion and hydroxide ion. SEM images show the uniform distribution of the microorganism inside bio-beads and the porous cross-linked structure of bio-beads which provides excellent mass transfer capacity.

关键词： Atrazine Polyvinyl alcohol(PVA) Embedment bio-bead

Delayed papillary muscle rupture after radiofrequency catheter ablation: A case report

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World Journal of Clinical Cases 2021年第20期9卷 5556-5561页

作者： Ze-Wei Sun bi-Feng Wu Xuan Ying bi-Qi zhang Lei Yao Liang-Rong Zheng Department of Cardiology Zhejiang UniversityHangzhou 310000Zhejiang ProvinceChina

BACKGROUND With an increased number of surgical procedures involving the mitral annular region,the risk of mitral valve prolapse(MVP)has also *** studies have reported that worsening of MVP occurred early after radiofrequency catheter ablation(RFCA)at papillary muscles in ventricular tachycardia(VT)patients with preoperative *** SUMMARY We report a case where MVP and papillary muscle rupture occurred 2 wk after RFCA in a papillary muscle originated VT patient without mitral valve regurgitation or prolapse *** patient then underwent mitral valve replacement with no premature ventricular contraction or *** the surgery,a papillary muscle rupture was *** examination showed necrosis of the papillary *** patient recovered after mitral valve *** Too many ablation procedures and energy should be avoided.

关键词： Mitral valve prolapse Radiofrequency catheter ablation Ventricular tachycardia Mitral valve replacement Dyspnea papillary muscles Case report

Observation on Clinical Effects of Electroacupuncture for Migraine Without Aura

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Journal of Acupuncture and Tuina Science 2014年第1期12卷 21-25页

作者： Fang Zhen zhang bi-meng Ningbo No.1 Hospital Zhejiang University of Traditional Chinese Medicine Department of Acupuncture and Moxibustion First People's Hospital School of Medicine Shanghai Jiaotong University

Objective: To observe the clinical effects of electroacupuncture(EA) for migraine without aura. Methods: The migraine patients in conformity with the conditions were randomly divided into two groups, 34 cases in each group. The treatment group was given EA and the control group was given the routine acupuncture treatment, to observe various pain indexes respectively before and one month after the treatment. Results: The general effect was remarkably better in the treatment group than that in the control group(P<0.05). Conclusion: EA is an effective therapy for migraine without aura.

关键词： Acupuncture Therapy Electroacupuncture Migraine Disorders Headache

Reversing multidrug resistance by RNA interference through the suppression of MDR1 gene in human hepatoma cells

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World Journal of Gastroenterology 2006年第21期12卷 3332-3337页

作者： Xiao-Ping Chen Qi Wang Jian Guan Zhi-Yong Huang Wan-Guang zhang bi-Xiang zhang Department of Surgery and Hepatic Surgery Center Tongji Hospital of Tongji Medical CollegeHuazhong University of Science and Technology Wuhan 430030China

AIM： To reverse the multidrug resistance （MDR） by RNA interference （RNAi）-mediated MDRI suppression in heparoma ***： For reversing MDR by RNAi technology, two different short hairpin RNAs （shRNAs） were designed and constructed into pGenSil-1 plasmid, respectively. They were then transfected into a highly adriarnycin-resistant HepG2 hepatorna cell line （HepG2/ADM）. The RNAi effect on MDR was evaluated by real-time PCR, cell cytotoxicity assay and rhodarnine 123 （Rh123） efflux assy. RESULTS： The stably-transfected clones showed various degrees of reversal of MDR phenotype. Surprisingly, the MDR phenotype was completely reversed in two transfected clones. CONCLUSION： MDR can be reversed by the shRNAmediated MDRI suppression in HepG2/ADM cells, which provides a valuable clue to make multidrug-resistant hepatoma cells sensitive to anti-cancer drugs.

关键词： Multidrug resistance ShRNA MDR1 Hepatocellular carcinoma

Down-regulation of Bcl-X_L by RNA interference suppresses cell growth and induces apoptosis in human esophageal cancer cells

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World Journal of Gastroenterology 2006年第46期12卷 7472-7477页

作者： Yong-En Xie En-Jie Tang Da-Rong zhang bi-Xuan Ren The Institute of Immunology and Molecular biology North Sichuan Medical College Nanchong 637007 Sichuan Province China

AIM： To determine the inhibitory effect of the vectorgenerated small interfering RNAs （siRNAs） on the expression of the BcI-XL gene in established human esophageal cancer cells, and to investigate the effect of the BcI-XL siRNAs on cell growth and apoptosis in esophageal cancer cells. METHODS： Three siRNA-expressing vectors targeting different sites of the Bcl-XL gene were constructed from pTZ-U6＋I vector. Cultured esophageal cancer cells were transfected with the siRNA-expressing vector （or the control vector） using lipofectamine 2000. BcI-XL gene expression was determined with semiquantitative RT- PCR assay and Western blotting. Among the three siRNA- expressing vectors, the most highly functional vector and its effect on cell growth and apoptosis in esophageal cancer ceils was further analyzed. RESULTS： Of the three siRNA-expressing vectors, siRNA- expressing vector No.1 was the most potent one which suppressed Bcl-XL mRNA production to 32.5% of that in the untreated esophageal cancer cells. Western blotting analysis showed that siRNA-expressing vector No.1 markedly down-regulated the expression of Bcl-XL in human esophageal cancer cells. Treatment of esophageal cancer cells with siRNA-expressing vector No.1 resulted in inhibition of cell growth and induction of apoptosis. CONCLUSION： Down-regulation of BcI-XL by vectorgenerated small interfering RNAs can suppress cell growth and induce apoptosis in human esophageal cancer cells.

关键词： Esophageal cancer BcI-XL RNA Interference Apoptosis

Combination of Micro-fluidic Chip with Fluorescence Correlation Spectroscopy for Single Molecule Detection

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Chinese Chemical Letters 2006年第4期17卷 521-524页

作者： Rui bi Pu Dun zhang Chao Qing DONG Ji Cun REN College of Chemistry ＆ Chemical Engineering Shanghai Jiaotong University Shanghai 200240

A single molecule detection technique was developed by the combination of a single channel poly （dimethylsiloxane）/glass micro-fluidic chip and fluorescence correlation spectroscopy （FCS）. This method was successfully used to determine the proportion of two model components in the mixture containing fluorescein and the rhodamine-green succinimidyl ester.

关键词： Fluorescence correlation spectroscopy micro-fluidic chip single molecule detection

Failure mode change and material damage with varied machining speeds:a review

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International Journal of Extreme Manufacturing 2023年第2期5卷 36-60页

作者： Jianqiu zhang binbin He bi zhang Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055People’s Republic of China

High-speed machining(HSM) has been studied for several decades and has potential application in various industries, including the automobile and aerospace industries. However,the underlying mechanisms of HSM have not been formally reviewed thus far. This article focuses on the solid mechanics framework of adiabatic shear band(ASB) onset and material metallurgical microstructural evolutions in HSM. The ASB onset is described using partial differential systems. Several factors in HSM were considered in the systems, and the ASB onset conditions were obtained by solving these systems or applying the perturbation method to the systems. With increasing machining speed, an ASB can be depressed and further eliminated by shock pressure. The damage observed in HSM exhibits common features. Equiaxed fine grains produced by dynamic recrystallization widely cause damage to ductile materials, and amorphization is the common microstructural evolution in brittle materials. Based on previous studies, potential mechanisms for the phenomena in HSM are proposed. These include the thickness variation of the white layer of ductile materials. These proposed mechanisms would be beneficial to deeply understanding the various phenomena in HSM.

关键词： high-speed machining adiabatic shear band subsurface damage dynamic recrystallization