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Incremental value of contrast echocardiography in the diagnosis of left ventricular noncompaction

null

《医学前沿（英文）》 2016年第10卷第4期页码 499-506 doi: 10.1007/s11684-016-0473-8

摘要：

Contrast echocardiography with left ventricular opacification (LVO) improves the definition of endocardium in two-dimensional echocardiography (2DE). This study was aimed to determine whether LVO offered added diagnostic value in noncompaction of left ventricular myocardium (NCVM). A total of 85 patients (40±20 years, 54 males) with suspected NCVM were subjected to transthoracic 2DE and LVO, and 40 healthy volunteers were examined with 2DE and assigned as control subjects. The location of NCVM, the thickness ratio of noncompacted to compacted myocardium (NCR), and the cavity size and ejection fraction of LV were quantified. Results revealed that NCVM was mainly located in the LV medium (53.2%), apical (46.2%) segments, and lateral wall (39.8%). The NCR obtained through LVO was greater than that detected through 2DE (4.2±1.3 vs. 3.3±1.2, P<0.001), and higher inter-correlations and less intra- and inter-observer variabilities were determined in the former than in the latter. The NCVM detection rates were also increased from 63.5% via 2DE to 83.5% via LVO and 89.4% via 2DE combined with LVO (2DE+ LVO) (P = 0.0004). The LV cavity size was greater and the LV ejection fraction (LVEF) was lower in the NCVM patients than in the control group (P<0.01). In the NCVM group, the LV cavity size was higher and the LVEF was lower in LVO than in 2DE (P<0.01). In conclusion, contrast echocardiography contributes significant sensitivity and reproducibility to routine transthoracic echocardiography in NCVM diagnosis. Therefore, this technique should be clinically performed to diagnose suspected NCVM.

关键词： echocardiography left ventricular noncompaction cardiomyopathy echo contrast media

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Splenic autotransplantation and oesophageal transection anastomosis in patients with portal hypertension (26 years clinical observation)

CHEN Jisheng, HUO Jinshan, ZHANG Hongwei, SHANG Changzhen, CHEN Rufu, ZHANG Jie, Obetien Mapudengo, CHEN Yajin, ZHANG Lei

《医学前沿（英文）》 2007年第1卷第1期页码 30-35 doi: 10.1007/s11684-007-0006-6

摘要： The surgical treatment methods for cirrhosis patients complicated with portal hypertension are complicated. In this study, we evaluated the effectiveness of a new treatment strategy: splenic auto-transplantation and oesophageal transection anastomosis on 274 patients from three aspects: clinical observation, splenic immunology and portal dynamics. From 1979 to 2005, 274 cirrhosis patients with portal hypertension who underwent the new treatment strategy were followed up to observe different clinical indexes, which were then compared with those of the traditional surgery treatment. From 1999 to 2002, a randomized control trial (RCT) was performed on 40 patients to compare their immune function after operation. From 1994 to 2004, another RCT was carried out on 28 patients to compare the portal dynamics through three-dimensional dynamic contrast enhanced MR angiography (3D DEC MRA) investigation after operation. Among 274 patients (mean age 41.8 years), the emergency operative mortality (4.4%), selective operative mortality (2.2%), complication rate (17.9%), morbidity of hepatic encephalopathy (<1%), bleeding rate of portal hypertension gastritis (PHG) (9.1%), and morbidity of hepatic carcinoma (8%) were similar to those under traditional operation; the spleen immunology function (Tuftsin, IgM) decreased among the groups 2 months after operation. Through 3D DCE MRA, the cross section area, the velocity and volume of blood flow of main portal vein decrease significantly after operation in both groups, the auto transplantation group was significantly lower in velocity and volume of blood flow than in the control group. Splenic auto transplantation and esophageal transection anastomosis are a safe, effective, and reasonable treatment strategy for portal hypertension with varicial bleeding. It can not only correct hypersplenism but also completely stanch blood, and auto transplanted spleen in the retroperitoneal space can preserve immune function and establish abroad collateral circulation.

关键词： esophageal transection oesophageal transection RCT dynamic contrast DCE MRA

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after percutaneous coronary intervention in coronary artery disease by using intracoronary myocardial contrast

WANG Hong, HUANG Lan, JIN Jun, SONG Yaoming, GENG Zhaohua, YU Xuejun, QIN Jun, ZHAO Gang, GAO Yunhua, LIU Zheng

《医学前沿（英文）》 2007年第1卷第1期页码 62-67 doi: 10.1007/s11684-007-0013-7

摘要： Detection of abnormal myocardial perfusion is crucial to the prognosis of patients with coronary artery disease (CAD) after they have undergone percutaneous coronary intervention (PCI). The objective of this study is to evaluate the effect of myocardial perfusion by three different methods intra-coronary myocardial contrast echocardiography (ICMCE), corrected thrombolysis in myocardial infarction frame count (CTFC), and coronary blood flow velocity (BFV) and to determine the value of these different methods in the evaluation of the effect of myocardial perfusion post-PCI. For the study sixty-eight patients were divided into four groups based on selective coronary angiography results: group A (normal coronary artery), group B (75% 95% coronary artery stenosis), group C (coronary artery stenosis >95%) and group D (acute total coronary occlusion). The effect of myocardial reperfusion was evaluated using the above mentioned three methods 15 min after PCI. IC-MCE was also performed before PCI in group D. The quantitative parameters of MCE involved: contrast peak intensity, time to peak intensity and area under the curve, representing myocardial blood volume, reperfusion velocity and myocardial blood flow, respectively. No difference was found in CTFC between the coronary artery stenosis group and the normal group. BFV was slower in group D than in group A (<0.05). The myocardial blood volume and the myocardial blood flow of the IC-MCE quantitative parameters were markedly lower in group C compared with those in group A (<0.05), and there were significant differences in the three MCE parameters between group D and group A (<0.05). For those patients with acute or total occlusion, the levels of myocardial perfusion before and after PCI were similar, as determined by IC-MCE and visually analyzed from 61 segments (<0.05). Quantitative IC-MCE evaluation of myocardial reperfusion is more accurate than with the other two methods. Moreover, with qualitative IC-MCE the level of myocardial reperfusion can be viewed directly and rapidly. Thus, the IC-MCE method is of great value to coronary artery disease (CAD) patients undergoing PCI, especially for those with acute myocardial infarction (AMI).

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Severe adhesive small bowel obstruction

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《医学前沿（英文）》 2012年第6卷第4期页码 436-439 doi: 10.1007/s11684-012-0221-7

摘要：

Adhesive small bowel obstruction is a frequent cause of hospital admission. Water soluble contrast studies may have diagnostic and therapeutic value and avoid challenging demanding surgical operations, but if bowel ischemia is suspected, prompt surgical intervention is mandatory. A 58-year-old patient was operated for extensive adhesive small bowel obstruction after having had two previous laparotomies for colorectal surgery, and had a complex clinical course with multiple operations and several complications. Different strategies of management have been adopted, including non-operative management with the use of hyperosmolar water soluble contrast medium, multiple surgical procedures, total parenteral nutrition (TPN) support, and finally use of anti-adherences icodextrin solution. After 2 years follow-up the patient was doing well without presenting recurrent episodes of adhesive small bowel obstruction. For patients admitted several times for adhesive small bowel obstruction, the relative risk of recurring obstruction increases in relation to the number of prior episodes. Several strategies for non-operative conservative management of adhesive small bowel obstruction have already addressed diagnostic and therapeutic value of hyperosmolar water soluble contrast. According to the most recent evidence-based guidelines, open surgery is the preferred method for surgical treatment of strangulating adhesive small bowel obstruction as well as after failed conservative management. Research interest and clinical evidence are increasing in adhesions prevention. Hyaluronic acid-carboxycellulose membrane and icodextrin may reduce incidence of adhesions.

关键词： post-operative intraperitoneal adhesions adhesive small bowel obstruction adhesiolysis antiadhesion treatments hyperosmolar water soluble contrast medium

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基于学习自适应区域选择的自动增强图像 None

Na LI, Jian ZHAN

《信息与电子工程前沿（英文）》 2019年第20卷第2期页码 206-221 doi: 10.1631/FITEE.1700125

摘要：如今数码相机被广泛用于日常摄影。然而，部分照片缺乏细节，需要增强处理。很多现有图像增强算法基于局部区域，而且同一图像所选区域尺寸通常是固定的。用户需手工选择合适的区域尺寸获取最佳图像增强效果。提出一种基于自适应区域选择的自动增强图像算法。该算法采用明暗两个通道，解决各类图像曝光问题。对网上爬取的大量自然图像统计分析获取阈值，自动选择用于通道提取的区域尺寸。该方法可自动增强模糊或者曝光不足/背光的图像，无需任何用户交互。实验结果表明，该算法对现有基于区域的图像增强算法有显著改进。

关键词：图像增强；对比度增强；暗通道；明通道；自适应区域处理

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非平面电极双稳态电润湿显示器件研究 Regular Papers-Research Articles

Han ZHANG, Xue-lei LIANG

《信息与电子工程前沿（英文）》 2019年第20卷第9期页码 1289-1295 doi: 10.1631/FITEE.1800167

摘要：双稳态电润湿显示器仅在状态切换时耗能，在状态稳定时无耗能，是一种非常有潜力的低能耗电子纸显示技术。本文设计和实现了通过常规光刻工艺制备一种非平面电极结构的双稳态电润湿器件。该器件不仅具备视频响应速度，而且有潜力实现可控的像素灰阶。与现有平面电极结构双稳态电润湿器件相比，该新型电极结构可实现更低驱动电压和更高对比度。

关键词：双稳态电润湿；非平面；控制电极；低电压；高对比度

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Numerical analysis of nonlinear dynamic behavior of earth dams

Babak EBRAHIMIAN

《结构与土木工程前沿（英文）》 2011年第5卷第1期页码 24-40 doi: 10.1007/s11709-010-0082-6

摘要： A numerical study is conducted to investigate the dynamic behavior of earth dams. The numerical investigation employs a fully nonlinear dynamic finite difference analysis incorporating a simple elastic perfectly plastic constitutive model to describe the stress-strain response of the soil and the Rayleigh damping to increase the level of hysteretic damping. The extended Masing rules are implemented into the constitutive model to explain more accurately the soil response under general cyclic loading. The soil stiffness and hysteretic damping change with loading history. The procedures for calibrating the constructed numerical model with centrifuge test data and also a real case history are explained. For the latter, the Long Valley (LV) earth dam subjected to the 1980 Mammoth Lake earthquake as a real case-history is analyzed and the obtained numerical results are compared with the real measurements at the site in both the time and frequency domains. Relatively good agreement is observed between computed and measured quantities. It seems that the Masing rules combined with a simple elasto-plastic model gives reasonable numerical predictions. Afterwards, a comprehensive parametric study is carried out to identify the effects of dam height, input motion characteristics, soil behavior, strength of the shell materials and dam reservoir condition on the dynamic response of earth dams. Three real earthquake records with different levels and peak acceleration values (PGAs) are used as input motions. The results show that the crest acceleration decreases when the dam height increases and no amplification is observed. Further, more inelastic behavior and more earthquake energy absorption are observed in higher dams.

关键词： earth dam numerical nonlinear response dynamic analysis earthquake dam height

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Construction of interfacial dynamic bonds for high performance lignin/polymer biocomposites

《化学科学与工程前沿（英文）》 2023年第17卷第10期页码 1372-1388 doi: 10.1007/s11705-023-2302-3

摘要： Lignin is the largest natural aromatic biopolymer, but usually treated as industrial biomass waste. The development of lignin/polymer biocomposites can promote the high value utilization of lignin and the greening of polymers. However, the weak interfacial interaction between industrial lignin and polymer induces poor compatibility and serious agglomeration in polymer owing to the strong intermolecular force of lignin. As such, it is extremely difficult to prepare high performance lignin/polymer biocomposites. Recently, we proposed the strategy of in situ construction of interfacial dynamic bonds in lignin/polymer composites. By taking advantage of the abundant oxygen-containing polar groups of lignin, we inserted dynamic bonding connection such as hydrogen bonds and coordination bonds into the interphase between lignin and the polymer matrix to improve the interfacial interactions. Meanwhile, the natural amphiphilic structure characteristics of lignin were utilized to construct the hierarchical nanophase separation structure in lignin/polymer composites. The persistent problems of poor dispersity and interfacial compatibility of lignin in the polymer matrix were effectively solved. The lignin-modified polymer composites achieved simultaneously enhanced strength and toughness. This concise review systematically summarized the recent research progress of our group toward building high-performance lignin/polymer biocomposites through the design of interfacial dynamic bonds (hydrogen bonds, coordination bonds, and dynamic covalent bonds) between lignin and different polymer systems (polar plastics, rubber, polyurethane, hydrogels, and other polymers). Finally, the future development direction, main challenges, and potential solutions of lignin application in polymers were presented.

关键词： lignin polymer interfacial dynamic bonds

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Molecular size characterization of heavy oil fractions in vacuum and solution by molecular dynamic simulation

Wenpo REN, Honggang CHEN, Chaohe YANG, Honghong SHAN,

《化学科学与工程前沿（英文）》 2010年第4卷第3期页码 250-256 doi: 10.1007/s11705-009-0281-7

摘要： Two kinds of heavy oils were fractionated into eight fractions by Liquid-Solid Adsorption Chromatography, respectively, and samples were collected to measure properties. According to the elemental analysis, molecular weight and H-NMR data, average molecular structures of polycyclic aromatic and heavy resin were constructed with improved Brown-Ladner (B-L) method and several corrections. And then, the most stable conformations of polycyclic aromatic and heavy resin in vacuum and toluene solution were obtained by molecular dynamic simulation, and the molecular size was gotten via the radius of gyration analysis. The results showed that the radius of gyration of polycyclic aromatic and heavy resin was 0.55–0.70 nm in vacuum and 0.60–0.90 nm in toluene solution. With molecular weight increasing, the molecular size in vacuum and toluene solution also increased. Due to the swelling behavior of solvent, the alkyl side chains of heavy oil molecule in solution were more stretched. Thus, the molecular size in toluene solution was larger than that in vacuum.

关键词： dynamic simulation molecular dynamic behavior molecule Adsorption Chromatography

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动态设定型板形板厚自动控制系统

张进之,段春华

《中国工程科学》 2000年第2卷第6期页码 67-72

摘要：

文章介绍了应用解析板形方程推出板形最佳轧制规程和板形板厚协调控制新方法。该方法的主要特点：系统中采用了静、动态负荷分配，动态设定厚度自动控制系统（DAGC）完成了板形板厚的闭环控制，在算法中采用了贝尔曼动态规划。新方法将会改变目前轧机设计和控制思想：设计合理刚度，强调调度计划、配置轧辊凸度和优化轧制规程等方面的作用，实现信息控制。

关键词：动态负荷分配板形最佳规程动态规划动态设定

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Modelling of dynamic contact length in rail grinding process

null

《机械工程前沿（英文）》 2014年第9卷第3期页码 242-248 doi: 10.1007/s11465-014-0305-y

摘要：

Rails endure frequent dynamic loads from the passing trains for supporting trains and guiding wheels. The accumulated stress concentrations will cause the plastic deformation of rail towards generating corrugations, contact fatigue cracks and also other defects, resulting in more dangerous status even the derailment risks. So the rail grinding technology has been invented with rotating grinding stones pressed on the rail with defects removal. Such rail grinding works are directed by experiences rather than scientifically guidance, lacking of flexible and scientific operating methods. With grinding control unit holding the grinding stones, the rail grinding process has the characteristics not only the surface grinding but also the running railway vehicles. First of all, it’s important to analyze the contact length between the grinding stone and the rail, because the contact length is a critical parameter to measure the grinding capabilities of stones. Moreover, it’s needed to build up models of railway vehicle unit bonded with the grinding stone to represent the rail grinding car. Therefore the theoretical model for contact length is developed based on the geometrical analysis. And the calculating models are improved considering the grinding car’s dynamic behaviors during the grinding process. Eventually, results are obtained based on the models by taking both the operation parameters and the structure parameters into the calculation, which are suitable for revealing the process of rail grinding by combining the grinding mechanism and the railway vehicle systems.

关键词： rail grinding contact length dynamic model Hamiltonian system grinding stone rail grinding car

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A job-insertion heuristic for minimizing the mean flowtime in dynamic flowshops

Guang GUO, Bo WU, Shuzi YANG

《机械工程前沿（英文）》 2011年第6卷第2期页码 197-202 doi: 10.1007/s11465-011-0211-5

摘要：

A new adaptive job-insertion based heuristic is presented to minimize the mean flowtime in a dynamic flowshop consisting of machines. Job orders arrive to the system randomly, and the job arrival or release dates are not known in advance. The heuristic is derived by inserting new jobs into the scheduled sequence as needed when the machine becomes free. Computation results indicate that the proposed heuristic performs 2.7%–10.8% better than the SPT dispatching rule, which is currently one of the most effective methods for minimizing the mean flowtime in dynamic flowshops.

关键词： scheduling dynamic flowshops flowtime heuristic mean flowtime

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Finding buckling points for nonlinear structures by dynamic relaxation scheme

Mohammad REZAIEE-PAJAND, Hossein ESTIRI

《结构与土木工程前沿（英文）》 2020年第14卷第1期页码 23-61 doi: 10.1007/s11709-019-0549-z

摘要： Dynamic Relaxation Method (DRM) is an explicit approach for solving the simultaneous systems of equations. In this tactic, the fictitious mass and damping are added to the static governing equations, and an artificial dynamic system is constructed. By using DRM for nonlinear analysis, the structural static equilibrium path is obtained. This outcome is extremely valuable, since it leads to the behavior of structures. Among the finding related to the structural static path are the critical and buckling points for nonlinear structures. In this paper, a new way for calculating the load factor is proposed by setting the external work zero. Mixing the dynamic relaxation scheme with external work technique has not been formulated so far. In all incremental-iterative methods, the load factor increment sign should be determinated by extra calculations. This sign leads to increase or decrease of the load increment. It is worth emphasizing that sign of the load factor increment changes at the load limit points. Therefore, the sign determinations are required in the common work control methods. These disadvantages are eliminated in the proposed algorithm. In fact, the suggested load factor depends only on the Dynamic Relaxation (DR) fictitious parameters. Besides, all DR calculations are performed via vector operation. Moreover, the load factor is calculated only by one formula, and it has the same relation in the all solution processes. In contrast to the arc length techniques, which requires the sign determined, the proposed scheme does not need any sign finding. It is shown that author’s technique is quicker than the other dynamic relaxation strategies. To prove the capability and efficiency of the presented scheme, several numerical tests are performed. The results indicate that the suggested approach can trace the complex structural static paths, even in the snap-back and snap-through parts.

关键词： load factor external work dynamic relaxation static equilibrium path large displacement

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Nonlinear analysis of cable structures using the dynamic relaxation method

Mohammad REZAIEE-PAJAND, Mohammad MOHAMMADI-KHATAMI

《结构与土木工程前沿（英文）》 2021年第15卷第1期页码 253-274 doi: 10.1007/s11709-020-0639-y

摘要： The analysis of cable structures is one of the most challenging problems for civil and mechanical engineers. Because they have highly nonlinear behavior, it is difficult to find solutions to these problems. Thus far, different assumptions and methods have been proposed to solve such structures. The dynamic relaxation method (DRM) is an explicit procedure for analyzing these types of structures. To utilize this scheme, investigators have suggested various stiffness matrices for a cable element. In this study, the efficiency and suitability of six well-known proposed matrices are assessed using the DRM. To achieve this goal, 16 numerical examples and two criteria, namely, the number of iterations and the analysis time, are employed. Based on a comprehensive comparison, the methods are ranked according to the two criteria. The numerical findings clearly reveal the best techniques. Moreover, a variety of benchmark problems are suggested by the authors for future studies of cable structures.

关键词： nonlinear analysis cable structure stiffness matrix dynamic relaxation method

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Effect of carbon black on the dynamic moduli of asphalt mixtures and its master curves

Chuangmin LI, Fanbo NING, Yuanyuan LI

《结构与土木工程前沿（英文）》 2019年第13卷第4期页码 918-925 doi: 10.1007/s11709-019-0526-6

摘要： Modulus is one of the main parameters during the design of asphalt pavement structure, the newest specifications of China gives the dynamic moduli ranges of commonly used asphalt mixtures with base asphalt (BA) or styrene-butadiene-styrene modified asphalt (SBS MA), while the moduli ranges of mixtures with carbon black modified asphalt (CB MA) are not recommended. To investigate the CB effect on the dynamic moduli of CB MA mixtures, one commonly used asphalt mixture (AC-20) was designed with BA, SBS MA, and CB MA, respectively. Then, the uniaxial compression dynamic modulus tests were conducted at different temperatures and loading frequencies, the master curves of asphalt mixtures were analyzed based on the time-temperature equivalence principle. The results show that ith increasing loading frequency, the temperature dependence of dynamic moduli of all asphalt mixtures tend to be less obvious. Both SBS and CB can decrease the temperature sensitivity of asphalt mixture, the SBS MA mixture has the lowest temperature sensitivity, followed by CB MA and BA mixture. In addition, CB and SBS can obviously improve the dynamic modulus of the BA mixture, enhance the anti-deformation performance of pavement structure, and the improvement effect of CB is almost the same with SBS.

关键词： dynamic modulus carbon black master curve modified asphalt asphalt mixture