期刊文献+
共找到5篇文章
< 1 >
每页显示 20 50 100
Magnetic resonance-based total liver volume and magnetic resonance-diffusion weighted imaging for staging liver fibrosis in mini-pigs 被引量:15
1
作者 Hang Li Tian-Wu Chen +9 位作者 Xiao-Li Chen Xiao-Ming Zhang Zhen-Lin Li Nan-Lin Zeng Li Zhou Li-Ying Wang Hong-Jie Tang Chun-Ping Li Li Li Xian-Yong Xie 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第48期7225-7233,共9页
AIM:To determine whether and how magnetic resonance imaging(MRI)-based total liver volume(TLV) and diffusion weighted imaging(DWI) could predict liver fibrosis.METHODS:Sixteen experimental mature mini-pigs(6 males,10 ... AIM:To determine whether and how magnetic resonance imaging(MRI)-based total liver volume(TLV) and diffusion weighted imaging(DWI) could predict liver fibrosis.METHODS:Sixteen experimental mature mini-pigs(6 males,10 females),weighing between 20.0 and 24.0 kg were prospectively used to model liver fibrosis induced by intraperitoneal injection of 40% CCl4 dissolved in fat emulsion twice a week for 16 wk,and by feeding 40% CCl4 mixed with maize flour twice daily for the subsequent 5 wk.All the survival animals underwent percutaneous liver biopsy and DWI using b = 300,500 and 800 s/mm2 followed by abdominal gadolinium-enhanced MRI at the 0,5th,9th,16th and 21st weekend after beginning of the modeling.TLV was obtained on enhanced MRI,and apparent diffusion coefficient(ADC) was obtained on DWI.Hepatic tissue specimens were stained with hematoxylin and Masson' s trichrome staining for staging liver fibrosis.Pathological specimens were scored using the human METAVIR classification system.Statistical analyses were performed to determine whether and how the TLV and ADC could be used to predict the stage of liver fibrosis.RESULTS:TLV increased from stage 0 to 2 and decreased from stage 3(r = 0.211;P < 0.001).There was a difference in TLV between stage 0-1 and 2-4(P = 0.03) whereas no difference between stage 0-2 and 3-4(P = 0.71).TLV could predict stage ≥ 2 [area under receiver operating characteristic curve(AUC) = 0.682].There was a decrease in ADC values with increasing stage of fibrosis for b = 300,500 and 800 s/mm2(r =-0.418,-0.535 and-0.622,respectively;all P < 0.001).Differences were found between stage 0-1 and 2-4 in ADC values for b = 300,500 and 800 s/mm2,and between stage 0-2 and 3-4 for b = 500 or 800 s/mm2(all P < 0.05).For predicting stage ≥ 2 and ≥ 3,AUC was 0.803 and 0.847 for b = 500 s/mm2,and 0.848 and 0.887 for b = 800 s/mm2,respectively.CONCLUSION:ADC for b = 500 or 800 s/mm2 could be better than TLV and ADC for b = 300 s/mm2 to pre-dict fibrosis stage ≥ 2 or ≥ 3. 展开更多
关键词 Magnetic resonance imaging Total liver volume Liver fibrosis Apparent diffusion coefficient Stage
下载PDF
Ultrasonic Pulse Signal Resonance Features in Layered CFRP Within Voids 被引量:1
2
作者 杨辰龙 陈越超 +1 位作者 WANG Zhe ZHENG Huifeng 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2017年第3期695-702,共8页
The ultrasonic pulse signal resonance features in layered carbon fiber reinforced plastic(CFRP) within voids were researched. The frequency domain model of acoustic wave propagation in multilayered medium was establ... The ultrasonic pulse signal resonance features in layered carbon fiber reinforced plastic(CFRP) within voids were researched. The frequency domain model of acoustic wave propagation in multilayered medium was established. Then the reflection coefficient of multilayered CFRP within voids was numerically calculated. The results are as follows. When the CFRP laminate is tested by ultrasonic whose center frequency is close to the CFRP inherent resonant frequency, the ultrasonic may generate resonance phenomenon in CFRP. If CFRP contains evenly distributed voids, the frequency of resonant signal and its amplitude all decrease with the increase of porosity. For the thick section CFRP within local concentrated voids, the local concentrated voids near testing surface will cause signal frequency reduction and the decrease of its amplitude. But the voids which exist in layers far away from testing surface almost have no influence on signal resonance. The ultrasonic pulse echo testing was conducted for thick section CFRP specimen. The analysis results of testing signals were in accordance with the results of the numerical calculation, showing that the reflection coefficient frequency response model can effectively explain the ultrasonic resonance phenomenon in layered CFRP within voids. 展开更多
关键词 carbon fiber reinforced plastic void resonance reflection coefficient frequency response
下载PDF
Effective electromechanical coupling coefficient of high-overtone bulk acoustic resonator 被引量:2
3
作者 LI Jian WANG Chenghao LIU Mengwei 《Chinese Journal of Acoustics》 CSCD 2017年第1期1-17,共17页
A high-overtone bulk acoustic resonator (HBAR) is composed of a substrate, a piezoelectric film and upper and lower electrodes, the influences of their structure parameter (thickness) and performance parameter (c... A high-overtone bulk acoustic resonator (HBAR) is composed of a substrate, a piezoelectric film and upper and lower electrodes, the influences of their structure parameter (thickness) and performance parameter (characteristic impedance) on effective electromechani- cal coupling coefficient K^2eff are investigated systematically. The relationship between K^2eff and these parameters is obtained by a lumped parameter equivalent circuit instead of distributed parameter equivalent circuit near the resonant frequency, and K^2eff at the resonance frequency closest to the given frequency is analyzed. The results show that K^2eff declines rapidly and oscillatorily with the continuous increase of the substrate thickness when the piezoelectric film thickness is fixed, and decreases inversely proportion to the thickness when the substrate thick-ness is greater than a certain value. With the ratio of the characteristic impedance of the substrate to the piezoelectric layer increasing, the maximum of K^2eff obtained from the vari- ation curve of K^2eff with the continuous increase of the piezoelectric film thickness decreases rapidly before reaching the minimum value, and later increases slowly. Fused silica with low impedance is appropriate as the substrate of HBAR to get a larger K^2eff. Compared with Al electrode, Au electrode can obtain larger K^2eff when the appropriate electrode thickness is selected. The revealed laws above mentioned provide the theoretical basis for optimizing parameters of HBAR. 展开更多
关键词 ZnO Effective electromechanical coupling coefficient of high-overtone bulk acoustic resonator high
原文传递
In situ NMR diffusion coefficients assessment of lithium ion conductor using electrochemical priors and Arrhenius constraint——A computational study 被引量:1
4
作者 Liang Deng Wen-Hui Yang +3 位作者 Xing Lyu Shu-Feng Wei Zheng Wang Hui-Xian Wang 《Chinese Chemical Letters》 SCIE CAS CSCD 2017年第2期362-366,共5页
In situ NMR measurements of the diffusion coefficients,including an estimate of signal strength,of lithium ion conductor using diffusion-weighting pulse sequence are performed in this study.A cascade bilinear model is... In situ NMR measurements of the diffusion coefficients,including an estimate of signal strength,of lithium ion conductor using diffusion-weighting pulse sequence are performed in this study.A cascade bilinear model is proposed to estimate the diffusion sensitivity factors of pulsed-field gradient using prior information of the electrochemical performance and Arrhenius constraint.The model postulates that the active lithium nuclei participating electrochemical reaction are relevant to the NMR signal intensity,when discharge rate or temperature condition is varying.The electrochemical data and the NMR signal strength show a highly fit with the proposed model according our simulation and experiments.Furthermore,the diffusion time is constrained by temperature based on Arrhenius equation of reaction rates dependence.An experimental calculation of Li_4Ti_5O_(12)(LTO)/carbon nanotubes(CNTs) with the electrolyte evaluating at 20 ℃ is presented,which the b factor is estimated by the discharge rate. 展开更多
关键词 Lithium ion conductor Diffusion coefficient Nuclear magnetic resonance Pulsed-field gradient Electrochemical priors
原文传递
Sintering behaviour and microwave dielectric properties of MgO-2B_(2)O_(3)--xwt%BaCu(B_(2)O_(5))-ywt%H_(3)BO_(3) ceramics 被引量:1
5
作者 Haiquan WANG Shixuan LI +2 位作者 Kangguo WANG Xiuli CHEN Huanfu ZHOU 《Journal of Advanced Ceramics》 SCIE CAS CSCD 2021年第6期1282-1290,共9页
This study investigates the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) series ceramics synthesised by solid-state reaction.According to the X-ray diffraction and micros... This study investigates the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) series ceramics synthesised by solid-state reaction.According to the X-ray diffraction and microstructural analyses,the as-prepared MgO-2B_(2)O_(3) ceramics possess a single-phase structure with a rod-like morphology.The effects of different quantities of H_(3)BO_(3) and BaCu(B_(2)O5)(BCB)on the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) ceramics were investigated.Accordingly,the optimal sintering temperature was obtained by adding 30 wt%H_(3)BO_(3) and 8 wt%BCB.We also reduced the sintering temperature to 825°C.Furthermore,the addition of 40 wt%H_(3)BO_(3) and 4 wt%BCB increased the quality factor,permittivity,and temperature coefficient of resonance frequency of MgO-2B_(2)O_(3) to 44,306 GHz(at 15 GHz),5.1,and-32 ppm/℃,respectively.These properties make MgO-2B_(2)O_(3) a viable low-temperature co-fired ceramic with broad applications in microwave dielectrics. 展开更多
关键词 low-temperature co-fired ceramics(LTCC) sintering temperature MgO-2B_(2)O_(3) H_(3)BO_(3) microwave dielectrics temperature coefficient of resonance frequency
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部