流产后宫内胎物组织残留的超声诊断

回顾性分析了４６例临床被证实为宫内胎物组织残留的病例。结果表明，流产后较长时间有不规则阴道流血，而作Ｂ超检查能发现特征性改变。声像图显示，子宫增大，宫内有异常光团和不规则液性暗区或宫腔局部膨隆，周边见很亮光条。认为诊断宫内残留组织，可以结合病只与声像技术较易诊断出来。本组超声诊断符合率达９８％。对减少因宫内残留造成的子宫收缩不良、不规则阴道流血等现象，避免并发感染及导致绒癌发生等不良后果，有重要的     

Ultrasonic velocity of binary systems at elevated pressures

Various empirical theories of ultrasonic velocity have been applied to three binary liquid mixtures, under pressures up to 200 MPa and their validity have been tested. A pressure dependent study of ultrasonic velocities has been made at 303.15 K. The agreement between theory and experiment is found to be quite satisfactory.     

Digital computation of transient characteristics of an induction motor on switched supply

A novel method of computing the nonlinear differential equations relating to the transient behaviour of an induction motor using a polynomial series, is presented. The stator and rotor currents and the angle of rotation are expressed as polynomial series dependent on time. These are then substituted into the differential equations of the induction motor to compute the polynomial coefficients and, consequently, the transient quantities. Since the equations are nonlinear, the computations are carried out using the step-by-step method. The stator and rotor currents, speed and torque are calculated for acceleration and braking conditions. The results are compared both analytically and experimentally.     

Probing particle-particle interactions in flocculated oil-in-water emulsions using ultrasonic attenuation spectrometry

The flocculation of silicone oil-in-water emulsions ( φ = 0.1) containing quasi-monodisperse droplets was studied by ultrasound. The ultrasonic attenuation spectra of emulsions with different particle sizes (200-1600 nm) were measured between 0.5 and 10 MHz using an interferometer. Flocculation was induced by adding excess sodium dodecyl sulphate micelles to the emulsions to increase the attractive forces between the droplets. Droplet flocculation decreased the ultrasonic attenuation at low frequencies because of overlap of the thermal waves caused by the close proximity of the droplets within the flocs. A mean-field model which takes into account this effect was used to determine the droplet volume fraction within the flocs and thus to estimate the distance between the droplets. Received 17 July 2000     

A Jump-U model of echo pattern for a sonar ranging module

Sonar is extensively used in robot as a range sensor and the time-of-flight (TOF) information of ultrasonic echo is frequently adopted in sonar applications. This paper proposes a Jump-U model of ultrasonic echo pattern based on TOF data for a sonar ranging module. The model is established through a data regression method, utilizing TOF data and the relation between the delay time and the bearing angle of the sensor as input parameters. Because the proposed model can explain the jump phenomenon of TOF data and the shape of TOF data is similar to character U, the model is named as Jump-U. Moreover, the model includes several parameters, and one of them is intensity factor which can be regard as a relative strength of ultrasonic echo. Experiments are conducted to verify the proposed model by measuring the echo’s TOF data of a plane with distances ranging from 100 to 200 cm. The results show a close agreement between simulation and measurements.     

New insights into the mechanisms of ultrasonic emulsification in the oil–water system and the role of gas bubbles

Ultrasonic emulsification (USE) assisted by cavitation is an effective method to produce emulsion droplets. However, the role of gas bubbles in the USE process still remains unclear. Hence, in the present paper, high-speed camera observations of bubble evolution and emulsion droplets formation in oil and water were used to capture in real-time the emulsification process, while experiments with different gas concentrations were carried out to investigate the effect of gas bubbles on droplet size. The results show that at the interface of oil and water, gas bubbles with a radius larger than the resonance radius collapse and sink into the water phase, inducing (oil–water) blended liquid jets across bubbles to generate oil-in-water-in-oil (O/W/O) and water-in-oil (W/O) droplets in the oil phase and oil-in-water (O/W) droplets in the water phase, respectively. Gas bubbles with a radius smaller than the resonance radius at the interface always move towards the oil phase, accompanied with the generation of water droplets in the oil phase. In the oil phase, gas bubbles, which can attract bubbles nearby the interface, migrate to the interface of oil and water due to acoustic streaming, and generate numerous droplets. As for the gas bubbles in the water phase, those can break neighboring droplets into numerous finer ones during bubble oscillation. With the increase in gas content, more bubbles undergo chaotic oscillation, leading to smaller and more stable emulsion droplets, which explains the beneficial role of gas bubbles in USE. Violently oscillating microbubbles are, therefore, found to be the governing cavitation regime for emulsification process. These results provide new insights to the mechanisms of gas bubbles in oil–water emulsions, which may be useful towards the optimization of USE process in industry.     

Suspension culture in a T-flask with acoustic flow induced by ultrasonic irradiation

Suspension culture is an essential large-scale cell culture technique for biopharmaceutical development and regenerative medicine. To transition from monolayer culture on the culture surface of a flask to suspension culture in a bioreactor, a pre-specified cell number must first be reached. During this period of preparation for suspension culture, static suspension culture in a flask is generally performed because the medium volume is not large enough to use a paddle to circulate the medium. However, drawbacks to this static method include cell sedimentation, leading to high cell density near the bottom and resulting in oxygen and nutrient deficiencies. Here, we propose a suspension culture method with acoustic streaming induced by ultrasonic waves in a T-flask to create a more homogeneous distribution of oxygen, nutrients, and waste products during the preparation period preceding large-scale suspension culture in a bioreactor. To demonstrate the performance of the ultrasonic method, Chinese hamster ovary cells were cultured for 72 h. Results showed that, on average, the cell proliferation was improved by 40% compared with the static method. Thus, the culture time required to achieve a 1000-fold increase could be reduced by 32 h (a 14% reduction) compared with the static method. Furthermore, the ultrasonic irradiation did not compromise the metabolic activity of the cells cultured using the ultrasonic method. These results demonstrate the effectiveness of the ultrasonic method for accelerating the transition to large-scale suspension culture.     

Effect of ultrasonic on the structure and quality characteristics of quinoa protein oxidation aggregates

Protein oxidation leads to covalent modification of structure and deterioration of functional properties of quinoa protein. The objective of this study was to investigate the effects of ultrasonic treatment on the functional and physicochemical properties of quinoa protein oxidation aggregates. In this concern, 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) was selected as oxidative modification of quinoa protein. The microstructure of quinoa protein displayed by scanning electron microscope (SEM) indicated that oxidation induced extensive aggregation, leading to carbonylation and degradation of sulfhydryl groups. Aggregation induced by oxidation had a negative effect on the solubility, turbidity, emulsifying stability. However, according to the analysis of physicochemical properties, ultrasonic significantly improved the water solubility of quinoa protein. The quinoa protein treated by ultrasonic for 30 min exhibited the best dispersion stability in water, which corresponded to the highest ζ-potential, smallest particle size and most uniform distribution. Based on the FT-IR, SDS-PAGE and surface hydrophobicity analysis, the increase of α-helix, β-turn and surface hydrophobicity caused by cavitation effect appeared to be the main mechanism of quinoa protein solubilization. In addition, the hydrophobic region of the protein was re-buried by excessive ultrasonic treatment, and the protein molecules were reaggregated by disulfide bonds. Microstructural observations further confirmed that ultrasonic treatment effectively inhibited protein aggregation and improved the functional properties of quinoa protein.     

Effect of ultrasound on the preparation of soy protein isolate-maltodextrin embedded hemp seed oil microcapsules and the establishment of oxidation kinetics models

In this study, microcapsules were prepared by spray drying and embedding hemp seed oil (HSO) with soy protein isolate (SPI) and maltodextrin (MD) as wall materials. The effect of ultrasonic power on the microstructure and characteristics of the composite emulsion and microcapsules was studied. Studies have shown that ultrasonic power has a significant impact on the stability of composite emulsions. The particle size of the composite emulsion after 450 W ultrasonic treatment was significantly lower than the particle size of the emulsion without the ultrasonic treatment. Through fluorescence microscopy observation, HSO was found to be successfully embedded in the wall materials to form an oil/water (O/W) composite emulsion. The spray-dried microcapsules showed a smooth spherical structure through scanning electron microscopy (SEM), and the particle size was 10.7 μm at 450 W. Fourier transform infrared (FTIR) spectroscopy analysis found that ultrasonic treatment would increase the degree of covalent bonding of the SPI-MD complex to a certain extent, thereby improving the stability and embedding effect of the microcapsules. Finally, oxidation kinetics models of HSO and HSO microcapsules were constructed and verified. The zero-order model of HSO microcapsules was found to have a higher degree of fit; after verification, the model can better reflect the quality changes of HSO microcapsules during storage.