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In the present study, two experimental examples as the applications by ultrafine bubble for railway fields are introduced. The first one was confirmed the cleaning effects of ultrafine bubble water on the brush cleaning machine used in the station buildings. It was found that the removal rate was increased by using ultrafine bubble in the brush cleaning machine compared to the tap water. However, it was also shown that the removal rate increased or decreased with respect to the number of rotations of the brush and the pressing force, and there were some conditions in which the effect of the ultrafine bubble could not be confirmed. In this experiment, it was shown that unevenness on the floor surface and dirt, and microbubbles grew from ultrafine bubble may be important for cleaning effect and understand of the mechanism. The second one was shown an interesting effect that the friction reduction effect by microcloth with ultrafine bubble water. In this experiment, the static frictional coefficient and dynamic frictional coefficient of the microcloth with tap water and ultrafine bubble water were measured on the glass plate. As the results, it was found that both frictional coefficients were decreased by ultrafine bubbles but when the glass plate was not dirty, both frictional coefficients did not decrease. [ABSTRACT FROM AUTHOR]

Fine bubbles are attracting social attention due to their many physical characteristics. However, the stability of fine bubbles remains unclear. Controlling its stability leads to the addition of new functions to the fine bubbles. It is important to elucidate the stabilization mechanism of the fine bubbles. We studied the stabilization of fine bubbles by molecular film covering that utilized molecular adsorption characteristics of the bubble surface. The molecular film was formed by two types of molecules. One was dialkylbipyridinium which was a positively charged organic molecule with hydrophobic groups, and the other was polystyrene sulfonate which was a negatively charged polymer. These two types of molecules interacted electrostatically to form a molecular film called an ion complex film on the surface of the bubble that was insoluble in water. The fine bubbles covered with the ion complex film were observed as a spherical structure by a digital microscope. Although the number decreased, a spherical structure was observed in the solution left for about one year. [ABSTRACT FROM AUTHOR]

We have researched the effect of micro-bubble CO2 injection and its mechanism toward the practical application of micro-bubble CO2 injection technology into Carbon Capture and Storage(CCS) and Enhanced Oil Recovery (EOR). In the first stage, we have carried out laboratory experiments and examined injection methods and developed tools as basic research. In the second stage, a field pilot test was conducted using a part of the Sarukawa oil field in Akita prefecture in order to verify the microbubble injection effect and mechanism evaluated based on basic research. In the test, the Huff and Puff method was adopted, CO2 injection for 10 days and flowback (production) for 7 days were carried out. The test is carried out by microbubble CO2 injection method and conventional CO2 injection method, and the test period is one month each. In the field test, the functionality of the tool was confirmed, that easy retrievableness in the well with slick line or wire line, the stable microbubble generation and injection, and the effect of the microbubble was evaluated as the improvement of CO 2 injectivity and storability. From the simulation model constructed based on the field test results, the mechanism of improving CO2 injectivity and storability was also evaluated. From these tests, it was confirmed that the microbubble injection technology can be applied in the field. [ABSTRACT FROM AUTHOR]

During the oil production process, oily waste water is coproduced at a rate several times that of oil. This water is known as produced water. Treatment levels and technologies are selected based on disposal method or reutilization objectives, environmental impacts, economics, and other such factors. For the treatment of produced water, the treatment system equipped with nitrogen microbubble flotation in conjunction with anthracite filtration and activated carbon adsorption was designed and examined. Polymer flooding is being used as an enhanced oil recovery (EOR) method in Oman. The quality of polymer flood produced water (PFPW) is different from produced water (PW) without polymer, it was clarified that aluminum sulfate (AS) is more effective than poly-aluminum chloride (PAC) as a flocculant. Based on the examination results, a 50 m3/day capacity pilot plant was designed, fabricated, and utilized to conduct produced water treatment trials, good oil removal was confirmed in all tests. It was also confirmed that this accompanied water treatment water could be used as irrigation water for agriculture by performing necessary higher order treatment. As a result, it was considered that the development as a new water source in the Middle East, where water resources are scarce, could be expected. [ABSTRACT FROM AUTHOR]

Bubbles with a diameter of 1 to 100 バ m are defined as microbubbles （hereinafter, this is called "MB"）, and are used for floatation separation because of their adhesion to suspended substances. However, there are few research reports on floatation separation, and standardization for device design has not been performed, so improving the efficiency of floatation separation devices has become an issue. Therefore, in this study, the experiments were carried out to clarify the floatation separation characteristics by microbubbles as a basic research of floatation separation by microbubbles. In the experiment, the soft flour was used as a suspended substance, and as basic characteristics, the state of adhesion with microbubbles, the relationship with bubble diameter, and the rising velocity rate were measured. In addition, as the actual floating separation performance, the concentration time with each initial concentration was investigated. The conclusions are as follows: About 60% of the adhered form of the microbubbles and the soft flour was observed as a form in which a single microbubble adhered to the soft flour. The number of microbubbles with a bubble diameter of 80-90 バ m was attached in the case of single microbubble attachment to flour is large. In the floating separation characteristics, floatation the soft flour concentration in the tank decreases sharply at the short time, and then gradually decreases. The higher the initial concentration, the longer the processing time required to reach the target concentration, but the tendency of the concentration decrease was the same. The final concentration remains around 20 ppm in all experimental conditions. These results are important for standardization of floatation separation characteristics in the future. [ABSTRACT FROM AUTHOR]

Microbubbles have various properties and are expected to be used in a wide range of fields. In this research, we focus on one of microbubble generators with a converging-diverging nozzle, i.e. a Venturi tube. In order to control bubble distribution of generated bubble diameter, knowledge of bubble generation mechanism in the tube is required. The purpose of this research is to clarify the effect of complex flow in a Venturi tube on bubble collapse. In this research, we focus on the change of pressure loss coefficient calculated from the pressure distribution in the tube and the sound pressure generated at the time of bubble collapse. For results of the experiment, the pressure loss coefficient increased due to the cavitation in the liquid single-phase flow. The same tendency was further obtained in the bubbly flow. It was also confirmed that the collapse behavior of bubbles differed depending on the inlet conditions, and sound pressure increased under conditions where rapid bubble collapse occurred. [ABSTRACT FROM AUTHOR]

Chemical solvents used for industrial washing process have a negative impact on the environment and the health of their users, and they are high-cost cleaning. In order to reduce the amount of chemical solvent used in the washing process, the non-chemical washing technology with microbubble is expected. We focus on the microbubble generator with a Venturi tube. This generator can generate the bubbles of hundred-micrometer diameter in high void fraction. And it is maintenance-free because of its simple structure. In this paper, authors introduce capability of oil washing with microbubbles generated using a Venturi tube and photoresist removal with Ozone microbubbles, which is friendly for the environment and no harm to the product. [ABSTRACT FROM AUTHOR]

Microbubbles (MB) are widely used as contrast agents in ultrasound diagnostic imaging because of its surpassing responsiveness to several MHz band. Recently, many researchers are trying to apply MB and ultrasound to drug delivery system (DDS) using MB as drug carrier or gene transfer. For clinical application of MB-DDS, it is crucial to manipulate microbubbles contactlessly, capture in a desired place, and destruct them near the target. In this research, we developed a promising method to capture and manipulate Sonazoid using a concave transducer which radiates focused ultrasound. We used concave transducers, witch calibers were 40 mm and focal distances were 40 mm. The center of the transducers was made a 20-mm diameter hole in to allow observation light to pass through. We found that MB in focused ultrasound field can manipulate moving ultrasound focus mechanically, it is mainly the effect of primary Bjerknes force. The accuracy of the two-dimensional manipulation was 10 μm order. The manipulation force by primary Bjerknes force was 6 pN in 5.46 MHz, 4 kPa ultrasound conditions. The accuracy of the manipulation is sufficiently better compared to the focal width radiated by the concave transducer. When estimating trapping force near a bubble cluster formed at the focal region, secondary Bjerknes force is mainly acting on MBs in 10 μm order distance. [ABSTRACT FROM AUTHOR]

Compulsive sedimentation of soil particles using coagulant is one of the solution for long-term turbid water in dams that has a bad effect on the environment of downstream rivers. We focus on allophane as a coagulant. The purpose of this study is to develop an atomization and transportation technique for allophane with a Venturi tube. We utilized the microbubble generator with a Venturi tube to atomize allophane. First, we visualized internal flow of the tube and measured diameter distribution of allophane after passing through the tube. As a result, allophane was atomized as small as that stirred for 10 minutes by ultrasonic, and it is suggested that allophane diameter hardly depends on liquid flow rate in the tube. Second, we throw allophane after passing through the tube into turbid water. As a result, the sedimentation of soil particles was promoted, and the turbidity of water was improved with the passage of time. The speed of sedimentation of soil particles is found to dependent on liquid and gas flow rate and presence of a Venturi tube. Third, we did transportation experiment of allophane. It is found that allophane is transported greatest under conditions of microbubble generation. Furthermore, we measured zeta potential of particles, and tried to reveal the mechanisms of turbid water treatment and transportation. [ABSTRACT FROM AUTHOR]

When the focused ultrasound of sufficient acoustic intensity in liquid interacts an air-liquid interface, atomization of the liquid occurs. This atomization process is well known that droplets are generated from the apexes of standing capillary waves with a wavelength that can be related to ultrasonic frequencies. In addition, there is a hypothesis that cavitation bubble oscillations can play a significant role in the pinch-off of droplets from capillary wave. The aim of this study is to clarify the influence of bubbles on the atomization of liquid. In this paper, we used the focused ultrasound with a frequency of 1 MHz; then, we observed the atomization process by using a high-speed photography. Also, we added the microbubbles to enhance the atomization of liquid. We found that threshold acoustic intensity of generating fine droplets becomes smaller. This result indicates that bubbles contribute significantly to the atomization of the liquid. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Japan Research Association for Textile End-Uses / Sen'i Seihin Shohi Kagaku is the property of Japan Research Association for Textile End-Uses / Sen'i Seihin Shohi Kagaku and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microbubble aeration is utilized usefully for chemical and biological processes which consume large amount of dissolved gas in liquid because the microbubbles have long residence time in liquid, large specific gas-liquid interfacial area and fast mass transfer rate. To design the industrial process using microbubble aeration, however, the fundamental characteristic and behavior of microbubbles have to be investigated at first. In this study, therefore, both shrinking and rising behaviors of a single microbubble are simultaneously observed. A single microbubble was induced from a fine nozzle into the bottom of a tall transparent vessel filled with ion-exchanged water in which dissolved gas was reduced previously with vacuum degassing. The single rising microbubble was chased with a high-speed video camera along the vessels height. The mass transfer rate was measured from the shrinking behavior of the single microbubble which was captured and analyzed from the video image. The smaller the diameter of a microbubble, the more rapidly it decreased. Finally, the microbubble was vanished. With reducing concentrations of oxygen and nitrogen dissolved in water, the shrinking rate of a microbubble became faster. The mass transfer from shrinking microbubble of either air or pure oxygen can be evaluated by the sum of oxygen transfer and nitrogen transfer, in which each mass transfer coefficient was estimated by the equation of Ranz and Marshall. The estimated behavior of the single shrinking microbubble was agreed well with the observation. It is understood in this study that both oxygen transfer and nitrogen transfer from shrinking microbubble into water occur independently in relatively low dissolved gas concentration in water. [ABSTRACT FROM AUTHOR]

Theranostics, a new medical term that combines therapeutics and diagnostics is considered an ideal system for medical care. Ultrasound is considered one of the most reasonable energies for the development of theranostics. Additionally, microbubbles, which are ultrasound contrast agents, have received considerable attention for their effectiveness in diagnosis and therapy. Microbubbles are composed of an inner gas and an outer shell composed of proteins or phospholipids. Under ultrasound exposure, the oscillation or collapse of microbubbles is induced depending on the intensity of the ultrasound. These mechanical effects are important for imaging, drug delivery, and ablation therapies. Therefore, it is essential that microbubbles reach the targeted site and induce mechanical effects to achieve effective and efficient diagnosis and therapy. We have previously developed novel microbubbles with high stability by optimizing the outer shell composition. Recently, microbubbles containing distearoylphosphatidyl glycerol showed high stability and prolonged circulation in the blood. These novel microbubbles may be useful for diagnosis and therapy. The combination of microbubbles and ultrasound has received considerable attention for brain-targeted drug delivery applications. We examined whether microbubbles can be used for brain-targeted drug delivery and evaluated the effect of the encapsulated gas on drug delivery. Thus, novel microbubbles combined with ultrasound can deliver molecules to the brain. Microbubbles containing perfluoropropane or perfluorobutane could efficiently deliver molecules to the brain. The novel microbubbles have long-circulating properties in the blood and could deliver molecules to the brain. The combination of novel microbubbles and ultrasound would contribute to the development of efficient thranostic systems.

Copyright of Kobunshi Ronbunshu is the property of Society of Polymer Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Theranostics is a term used to describe the combination of diagnostic and therapeutic functions in a single agent. Ultrasound, for example, is a good tool for theranostics due to its multi-potency as both a diagnostic tool using sonography, and as a therapeutic, i.e., by high intensity focused ultrasound (HIFU). Likewise, microbubbles and nanobubbles are not only used as contrast imaging agents, but also as enhancers of drug delivery. Recently, the combination of these bubbles with low intensity ultrasound has been utilized as an effective drug delivery system. We have implemented a similar technique by combining bubbles and ultrasound to study cancer gene therapy and chemotherapy. In addition, we have used high intensity ultrasound as a method for directly damaging tumor cells, thus serving as a cancer therapy. For effective cancer treatment, however, the properties of the bubbles are of utmost importance. Currently, we are applying these bubbles to various therapeutic strategies in cancer treatment. In this session, we would like to introduce the feasibility study of our use of these bubbles in cancer treatment.