Stabilization of Gas Bubbles Released from Water-Soluble Carbohydrates Using Amphiphilic Compounds: Preparation of Formulations and Acoustic Monitoring of Bubble Lifetime
The ultrasound contrast agents Echovist® and Levovist® (Bayer AG, Schering AG, Germany) are based on the release of gas bubbles from milled α-d-galactose. In diagnostic ultrasound, for this class of contrast agents, there is a need for prolonged contrast duration. To investigate if new carbohydrate compositions could prolong the lifetime of the gas bubbles, α-d-galactose was mixed with other carbohydrates or amphiphiles with varying log P. Acoustic attenuation vs. time (390 s) area under the curve (A390) and bubble half-time (t½) were used as measures of prolonged lifetime of gas bubbles. The products, to which 0.1% of a lipophilic carboxylic acid (5β-cholanic acid, behenic acid, and melissic acid) has been added, showed more than 5, 7 and 11 times enhancement of A390, respectively, compared with the reference compound 2 (RC2) corresponding to the commercial product Levovist®. The half-time t ½ of the same compounds was prolonged more than 6 times compared with RC2. A partial least square (PLS) statistical analysis confirmed that, for additives, high log P carboxylic acids lead to the highest A390. The present results bear a promise of products with a more persistent in vivo ultrasound contrast effect than the commercially available agents.
Effect of ultrasonic treatment on swine wastewater solubilization.
In order to accelerate hydrolysis known to be the rate-limiting step of the overall digestion process for swine wastewater, an ultrasonic treatment process was tested for the solubilization of the swine wastewater. The effectiveness of ultrasonic solubilization of the swine wastewater under various operational conditions was compared by means of an increment of soluble organics in the treated swine wastewater and the hydrolysis rate constant. Ultrasonic treatment resulted in the high degree of solubilization of particulate organics in the swine wastewater and the degree of solubilization increased with increasing supplied energy. The highest extent of an increment of SCOD concentration and SCOD/TCOD ratio at the end of the operation time of 60 min was 109.7 and 117.5%, respectively, under 120 W power output and 20(o)C operating temperature conditions. The observed highest hydrolysis rate constant described by pseudo-first order rate constant was 2.94 h(-1) under the same conditions. Based on the estimated activation energy from modeling using the Arrhenius equation, ultrasonic solubilization of the swine wastewater under higher supplied energy conditions was more dependent on the operating temperature, which was consistent with the experimentally obtained results. Based on the investigation into the effect of gas type and gas delivery methods for ultrasonic solubilization of the swine wastewater, oxygen gas bubbling through the liquid showed the highest degree of an increment of soluble organics possibly attributed to the influent of oxygen in an increase of radicals during the sonolysis.
Analysis of a coaxial-to-waveguide adaptor including a discended probe and a tuning post
A field matching analysis of a coaxial-to-waveguide adaptor incorporating a disc-ended probe and a tuning post is presented. In this analysis, the tuning post is considered as a short-circuited second probe. A computer algorithm for calculating the input impedance of this structure is developed. This algorithm is used to investigate and improve the operation of a commercially available coaxial-to-waveguide adaptor. >