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81.
目的应用实时三维超声心动图探讨肺源性心脏病患者右心室收缩功能的价值,比较右心造影对测值的影响。方法选择肺源性心脏病代偿组、失代偿组、正常对照组各20例分别进行造影前、后实时三维超声的采集成像,计算右心室舒张末容积(RVEDV)、右心室每博输出量(RVSV)和右心室射血分数(RVEF),并根据心内膜是否清晰可辨分为心内膜边界清晰者、心内膜边界欠清晰者,比较两者三维超声参数的组间差异。结果代偿组、失代偿组RVEDV较对照组均明显增加,RVEF值减低(均P<0.01),代偿组与对照组RVSV差异无统计学意义(P>0.05),但失代偿组RVSV与代偿组、对照组差异有统计学意义(P<0.05);失代偿组RVEDV较代偿组明显增大,RVEF明显减低(均P<0.01)。心内膜边界欠清晰者造影后较造影前RVEDV、RVEF差异均有统计学意义(均P<0.05)。结论实时三维超声能够客观地反映肺源性心脏病代偿期与失代偿期右心室收缩功能的变化,右心声学造影改善了心内膜边界的可识别性,提高了右心室收缩功能测值的可靠性。 相似文献
82.
Synthesis of CuS nanoparticles loaded on activated carbon composite for ultrasound‐assisted adsorption removal of dye pollutants: Process optimization using CCD‐RSM,equilibrium and kinetic studies 下载免费PDF全文
In this study, the CuS nanoparticles loaded on activated carbon (CuS‐NPs‐AC) composite was synthesized and then, characterized by XRD and FE‐SEM analyses. The prepared composite was used as a potential adsorbent for the simultaneous ultrasound‐assisted removal of Indigo Carmine (IC) and Safranin‐O (SO). The CuS‐NPs‐AC dose (0.01‐0.03 g), sonication time (1‐5 min), initial SO concentration (5‐15 mg L‐1) and initial IC concentration (5‐15 mg L‐1) as expectable effective parameters were studied by central composite design (CCD) under response surface methodology (RSM) to obtain an useful knowledge about the effect of simultaneous interaction between IC and SO on their removal percentage. The optimum SO and IC removal percentages were determined to be 98.24 and 97.15% at pH = 6, 0.03 g of the CuS‐NPs‐AC, 3 min sonication time, 12 and 10 mg L‐1 of IC and SO. The values of coefficient of determination (R2) for SO and IC were 0.9608 and 0.9796, respectively, indicating the favorable fitness of the experimental data to the second order polynomial regression model. The isotherm data were well correlated with Freundlich model. The maximum monolayer adsorption capacities of 87.5 and 69.90 mg g‐1 at room temperature for IC and SO in the investigated binary system expressed the high efficiency of the novel adsorbent for water cleanup within a short time. The investigation of correlation between time and rate of adsorption revealed that IC and SO adsorption onto the CuS‐NPs‐AC followed pseudo‐second‐order and intra‐particle diffusion simultaneously. 相似文献
83.
4(3H)‐Quinazolinones were synthesized in high yields by one‐pot three‐component condensation of anthranilic acid, carboxylic acid and aniline in the presence of ionic liquid such as 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate (BMImBF4) as catalyst under solvent free and neutral conditions. 相似文献
84.
Pollen-shape (spiked sphere) hydroxyapatite (HA) particles for drug carrier application are studied. The particle shape and size effect on flow characteristics and deposition are assessed. The pollen-shape HA particles are synthesized to have comparable size as typical carrier particles with mean diameter of 30-50 m and effective density less than 0.3 g/cm 3 . The flow behaviors of HA and commonly used lactose (LA) carrier particles are characterized by the Carr's compressibility index (CI). The HA particle... 相似文献
85.
Ion hydration has been studied for potassium iodide solutions with concentrations from 0 to 51 wt.% at temperatures from 288.15 to 308.15 K based on ultrasonic measurements and molar adiabatic compressibility data. For hydration complexes, structural characteristics have been determined. The structure of noncoordinated water plays a significant role even in concentrated solutions. An electrostatic ion field has a strong effect on the temperature dependence of the molar volume of hydration water. A method for the precise determination of the total solvation boundary is presented. 相似文献
86.
Using the improved thermodynamic method, the acoustic non-linearity parameter B/A of binary biological mixtures — such as pig blood, sheep blood and bovine blood — is measured in order to test the mixture rules proposed by Apfel and Sehgal. The results show that the B/A values of the above-mentioned blood decrease with an increasing volume fraction of water. The B/A value varies linearly with the volume fraction of protein. It is also shown that, treated as a binary mixture, the blood obeys the trend that the B/A value varies with the volume of water. This is in agreement with the rules proposed by Apfel and Sehgal. However, the measured B/A value is not exactly equal to that of the mixture rules. 相似文献
87.
To facilitate practical medical applications such as cancer treatment utilizing focused ultrasound and bubbles, a mathematical model that can describe the soft viscoelasticity of human body, the nonlinear propagation of focused ultrasound, and the nonlinear oscillations of multiple bubbles is theoretically derived and numerically solved. The Zener viscoelastic model and Keller–Miksis bubble equation, which have been used for analyses of single or few bubbles in viscoelastic liquid, are used to model the liquid containing multiple bubbles. From the theoretical analysis based on the perturbation expansion with the multiple-scales method, the Khokhlov–Zabolotskaya–Kuznetsov (KZK) equation, which has been used as a mathematical model of weakly nonlinear propagation in single phase liquid, is extended to viscoelastic liquid containing multiple bubbles. The results show that liquid elasticity decreases the magnitudes of the nonlinearity, dissipation, and dispersion of ultrasound and increases the phase velocity of the ultrasound and linear natural frequency of the bubble oscillation. From the numerical calculation of resultant KZK equation, the spatial distribution of the liquid pressure fluctuation for the focused ultrasound is obtained for cases in which the liquid is water or liver tissue. In addition, frequency analysis is carried out using the fast Fourier transform, and the generation of higher harmonic components is compared for water and liver tissue. The elasticity suppresses the generation of higher harmonic components and promotes the remnant of the fundamental frequency components. This indicates that the elasticity of liquid suppresses shock wave formation in practical applications. 相似文献
88.
Dr. Avraam I. Isayev Sergei P. Yushanov Seok-Ho Kim Victor Yu. Levin 《Rheologica Acta》1996,35(6):616-630
Continuous ultrasonic devulcanization of ground tire rubber (GRT) and styrene-butadiene rubber (SBR) is considered. Experiments are performed under various processing conditions. Two recipes of SBR with different amounts of polysulfidic linkages are utilized. Gel fraction and crosslink density of devulcanized rubbers are measured and a unique relationship between them is established. Die characteristics with and without imposition of ultrasonic waves are determined. Devulcanized samples are revulcanized and mechanical properties are measured. In some cases, properties of revulcanized SBR samples exceeded those of virgin vulcanizates. This is explained based on the presence of a double network in the revulcanized rubber. A modification of acoustic cavitation and flow modeling of ultrasonic devulcanization of SBR and GRT is proposed using a concept of effective viscosity characterizing the flow of vulcanized particles before devulcanization combined with a shear rate, temperature and gel fraction-dependent viscosity of devulcanized rubber. Velocity, shear rate, pressure, and temperature field along with gel fraction, crosslink density and number of bonds broken are simulated. Predicted data on gel fraction, crosslink density, and pressure using the present modification of the model are found to be closer to experimental data then previously reported.Dedicated to the memory of Professor Tasos C. Papanastasiou 相似文献
89.
Methods based on guided ultrasonic waves are gaining increasing attention for the non-destructive inspection and condition
monitoring of multi-wire strands used in civil structures such as prestressing tendons and cable stays. In this paper we examine
the wave propagation problem in seven-wire strands at the level of the individual wires comprising the strand. Through a broad-band,
laser ultrasonic setup and a time—frequency wavelet transform processing, longitudinal and flexural waves are characterized
in terms of dispersive velocity and frequency-dependent attenuation. These vibrating frequencies propagating with minimal
losses are identified as they are suitable for long-range inspection of the strands. In addition, the wave transmission spectra
are found to be sensitive to the load level, suggesting the potential for continuous load monitoring in the field. 相似文献
90.
The sonochemical synthesis of gold nanoparticles (GNPs) with different shapes and size distributions by using high‐intensity focused ultrasound (HIFU) operating at 463 kHz is reported. GNP formation proceeds through the reduction of Au3+ to Au0 by radicals generated by acoustic cavitation. TEM images reveal that GNPs show irregular shapes at 30 W, are primarily icosahedral at 50 W and form a significant amount of nanorods at 70 W. The size of GNPs decreases with increasing acoustic power with a narrower size distribution. Sonochemiluminescence images help in the understanding of the effect of HIFU in controlling the size and shapes of GNPs. The number of radicals that form and the mechanical forces that are generated control the shape and size of the GNPs. UV/Vis spectra and TEM images are used to propose a possible mechanism for the observed effects. The results presented demonstrate, for the first time, that the HIFU system can be used to synthesise size‐ and shape‐controlled metal nanoparticles. 相似文献