Effect Of Air Bubbles Research Articles

水中聴覚における外耳道の空気泡の影響について

In order to examine the effects of air bubble in the ear canal for underwater hearing, detailed measurement of minimum audible field (MAF) in audio frequency (50Hz-8kHz) and comparison of loudness were carried out at two conditions as below, 1) the air bubble remains in the ear canal and 2) the ear canal is filled with water. As the result, in the high frequency region over about 300 Hz, it is highly sensitive to hearing in the case that the air bubble remained in the ear canal. In the low frequency region under 300 Hz, it becomes more sensitive in the case that the ear canal was filled with the water by removing the air bubble.The reverse phenomenon of “hearing” at about 300 Hz is explained by difference between frequency characteristics of the occlusion effect (air conduction) and the effect in which the ear canal was filled with the water (bone conduction).

A novel nanolayer biosensor principle

A method for eliminating the mass transport limitation on biosensor surfaces is introduced. The measurement of macromolecular binding kinetics on plane surfaces is the key objective of many evanescent wave (e.g. total internal reflection fluorescence (TIRF)), and surface plasmon resonance (SPR) based biosensor systems, allowing the determination of binding constants within minutes or hours. However, these methods are limited in not being rigorously applicable to large macromolecules like proteins or DNA, since the on-rates are transport limited due to a Nernst diffusion layer of 5–10 μm thickness. Thus, for the binding of fibrinogen (340 kDa) to a surface current SPR biosensors will show a mass transport coefficient of ca. 2×10 −6 m/s. In a novel approach with an immiscible fluid vesicle (e.g. air bubble), it has been possible to generate nanoscopic fluid films of ca. 200 nm thickness on the sensor surface of an interfacial TIRF rheometer system. The thickness of the liquid film can be can be easily probed and measured by evanescent wave technology. This nanofilm technique increases the mass transport coefficient for fibrinogen to ca. 1×10 −4 m/s eliminating the mass transport limitation, making the binding rates reaction-rate limited. From the resulting exponential kinetic functions, lasting only 20–30 s, the kinetic constants for the binding reaction can easily be extracted and the binding constants calculated. As a possible mechanism for the air bubble effect it is suggested that the aqueous fluid flow in the rheometer cell is separated by the air bubble below the level of the Nernst boundary layer into two independent laminar fluid flows of differing velocity: (i) a slow to stationary nanostream ca. 200 nm thick strongly adhering to the surface; and (ii) the bulk fluid streaming over it at a much higher rate in the wake of the air bubble. Surprising properties of the nanofluidic film are: (i) its long persistence for at least 30–60 s after the air bubble has passed (2.5 s); and (ii) the absence of solute depletion. It is suggested that a new liquid–liquid interface (i.e. a “vortex sheet”) between the two fluid flows plays a decisive role, lending metastability to the nanofluidic film and replenishing its protein concentration via the vortices—thus upholding exponential binding kinetics. Finally, the system relaxes via turbulent reattachment of the two fluid flows to the original velocity profile. It is concluded that this technique opens a fundamentally novel approach to the construction of macromolecular biosensors.

Effects of air bubbles and tube transportation on blood oxygen tension in arterial blood gas analysis.

Pneumatic tube transport has been reported to aggravate the error in partial pressure of oxygen (PO(2)) measurements caused by air bubbles. The aim of this study was to clarify the effect of manual and pneumatic tube methods of sample transportation and different amounts of air bubbles on arterial blood gas analysis. Blood gas samples from 15 patients and a pooled wasted blood mixture with 3 different levels of PO(2) were analyzed to determine the effects of air bubbles and manual versus pneumatic tube transportation on PO(2) levels. PO(2) increased significantly in samples containing 10% air bubbles and was exaggerated by pneumatic tube transport (from 115.63 +/- 9.31 mm Hg to 180.51 +/- 11.29 mm Hg, p < 0.001). In samples with low PO(2) ( approximately 30 mm Hg), the measurement was not aberrant regardless of the method of transportation or the amount of air bubbles contained in the specimen. However, in samples with medium and high PO(2) (> 70 mm Hg), aberrances in measurements were noted even with only 0.5% air bubbles and regardless of whether the sample was transported by manual methods or pressurized tube. The increments of PO(2) correlated positively with the amount of air introduced into the specimens. Thus, the measured PO(2) increased 8.13 and 31.77 mm Hg when 0.5% and 10% air bubbles were introduced, respectively, to samples with medium PO(2) (p < 0.05). The interaction between the amount of air bubbles and the method of transportation was significant (p < 0.001). Trapped air in the syringe should be expelled as thoroughly as possible, since the presence of only 1% air bubbles can result in aberrance in PO(2) measurement. Samples for blood gas analysis should be carried in ambient pressure to the laboratory because pneumatic tube delivery systems significantly aggravate the air bubble-related aberrance in PO(2) measurement.

Effects of flow speed, flow pattern and air bubbles on pressure loss in slurry pipelines

Pressure loss is an important factor in the design of a pipeline transportation system. To investigate the effects of flow speed, flow pattern and air bubbles on pressure loss in pumping a slurry or grout, a pipeline transportation system was established, and experiments that focused on the effects of flow patterns were performed. Curves describing the relationship of pressure gradient to velocity have two distinct segments, indicating laminar flow and turbulent flow. No significant difference in pressure loss was observed between the different flow patterns, although the straight and tangential flows showed a slight improvement to the whole system, and better performance was observed over a short distance. In terms of energy usage, bubbles introduced into the slurry require extra energy. A larger-diameter pipe is more efficient in a pipeline system.

Role of oceanic air bubbles in atmospheric correction of ocean color imagery.

Ocean color is the radiance that emanates from the ocean because of scattering by chlorophyll pigments and particles of organic and inorganic origin. Air bubbles in the ocean also scatter light and thus contribute to the water-leaving radiance. This additional water-leaving radiance that is due to oceanic air bubbles could violate the black pixel assumption at near-infrared wavelengths and be attributed to chlorophyll in the visible. Hence, the accuracy of the atmospheric correction required for the retrieval of ocean color from satellite measurements is impaired. A comprehensive radiative transfer code for the coupled atmosphere--ocean system is employed to assess the effect of oceanic air bubbles on atmospheric correction of ocean color imagery. This effect is found to depend on the wavelength-dependent optical properties of oceanic air bubbles as well as atmospheric aerosols.

Study of the performance of physical water treatment with a solenoid coil to prevent mineral fouling. Part 2: Effect of air bubbles

The purpose of the present study was to investigate the effect of air bubbles on mineral fouling in a heat exchanger with a cooling-tower water. Two different tests were conducted in a concentric-tube heat exchanger at 12 cycles of concentration: no-treatment, and a physical water treatment (PWT). A small flow velocity of 0.83 m/s and a high heat flux of 22.5x10 4 W/m 2 were chosen to accelerate the fouling in the heat exchanger. Air bubbles from the cooling water adhered to the heat-transfer surface made of a smooth copper tube, significantly affecting the overall fouling process. The fouling started from the heat-transfer surface covered by the air bubbles and then spread around the area not covered by the bubbles. The fouling resistance in the case with PWT was approximately 27% less than that in the no-treatment case, indicating that the PWT could be useful in mitigating mineral fouling even in the case of a low flow velocity where air bubbles adversely affect the fouling process.

Effects of Air Bubbles on B-Value and P-Wave Velocity of a Partly Saturated Sand.

ABSTRACT The effects of the size and solubility of an air bubble on the B-value and P-wave velocity of a partly saturated sand are discussed. The relations between B-value and P-wave velocity are determined for large triaxial specimens with Dr = 64% and 84%. Theoretical formulas have been derived for determining the P-wave velocity of a partly saturated sand containing air bubbles. It is shown that: (1) the solubility of air bubbles in the pore-water significantly affects the relations between B-value and P-wave velocity; (2) the practical coefficient of solubility of air bubble pressured in the pore-water is about 0.002; (3) the B-value and P-wave velocity increase with a decrease in the air bubble size. This tendency is significant, when the diameter of the air bubble is less than about 0.005 mm.

Analysis of Bubbly Lubrication in Journal Bearings.

The effect of air bubbles evenly distributed in lubricating oil on the bearing performances is analyzed theoretically. The Reynolds equation for the bubbly lubricant in a steady-state and isothermal condition is solved with an iterative numerical method. Surface tension and the radius of bubble are taken into account in the analysis. It is assumed that bubbles move along streamlines and do not split apart or coalesce. The density and the viscosity of air-oil mixture are treated as functions of oil film pressure and the volume fraction of air. Numerical results show that the load carrying capacity of a journal bearing increases as bubbles in the supplied lubricant become smaller or the surface tension is getting larger. The load carrying capacity increases as the volume fraction increases up to a critical volume fraction that gives maximum load carrying capacity. Beyond the critical volume fraction, it decreases as the volume fraction increases.

The Effect of Air Bubbles and Headspace on the Aqueous Concentrations of Volatile Organic Compounds in Sampling Vials

AbstractThe presence of headspace and air bubbles in volatile organic analysis sampling vials lowers the actual aqueous concentration of these compounds due to the partitioning of solutes into the gaseous phase. This could make the sample invalid for analysis.In this work, the effects of air bubbles and headspace on the aqueous concentration of 60 volatile organic compounds listed in U.S.Environmental Protection Agency (U.S. EPA) Method 8260 were evaluated experimentally and theoretically. The results showed that for air to water ratios of 1 to 20 and less, there was no significant effect on the aqueous concentrations of target organic solutes in the sampling vials. When the air to water ratio was increased to 1 to 10, the recovery rates of four organic compounds were lower than the control. Laboratory experiments on sampling vials showed that the presence of air bubbles or headspace with the volumetric air to water ratios of 1 to 20 and less do not produce any significant effect on the original concentrations for most targeted volatile organic compounds.The experimental results also indicated that in 40 mL sampling vials with headspace range of 2 to 8 mL, the recovery rates of most volatile organic compounds with high values of Henry's law constant (&gt; 0.01 Atm m3/mol. at 25°C) were larger than the calculated rates.

The Effect of Bubbly Oil on the THD Lubrication of Tilting-pad Journal Bearings Subjected to Rotating Unbalance Load

Little work has been published on the contribution of entrained air and/or gas bubbles on the lubricant viscosity and hence on the hydrodynamic performance of bearings. In this work, a thermo-hydrodynamic analysis of the performance of dynamically loaded tilting-pad journal bearing lubricated by bubbly oil is carried out. The non-steady Reynolds equation for compressible fluid and the energy equation are solved iteratively using finite difference method to study the effect of air bubbles on the bearing performance characteristics. The effect of bubbles content on the lubricant viscosity is considered.

Pressure drop and heat transfer of a mercury single-phase flow and an air–mercury two-phase flow in a helical tube under a strong magnetic field

For the reduction of a large magneto-hydrodynamic (MHD) pressure drop of a liquid metal single-phase flow, a liquid metal two-phase flow cooling system has been proposed. As a fundamental study, MHD pressure drops and heat transfer characteristics of a mercury single-phase flow and an air–mercury two-phase flow were experimentally investigated. A strong transverse magnetic field relevant to the fusion reactor conditions was applied to the mercury single-phase flow and the air–mercury two-phase flow in a helically coiled tube that was inserted in the vertical bore of a solenoidal superconducting magnet. It was found that MHD pressure drops of a mercury single-phase flow in the helically coiled tube were nearly equal to those in a straight tube. The Nusselt number at an outside wall was higher than that at an inside wall both in the mercury single-phase flow in the absence and presence of a magnetic field. The Nusselt number of the mercury single-phase flow decreased, increased and again decreased with an increase in the magnetic flux density. MHD pressure drops did not decrease appreciably by injecting air into a mercury flow and changing the mercury flow into the air–mercury two-phase flow. Remarkable heat transfer enhancement did not appear by the air injection. The injection of air into the mercury flow enhanced heat transfer in the ranges of high mercury flow rate and low magnetic flux density, possibly due to the agitation effect of air bubbles. The air injection deteriorated heat transfer in the range of low mercury flow rates possibly because of the occupation of air near heating wall.

Inertia effects in circular squeeze films containing a central air bubble

An analysis of the laminar squeezing flow of an incompressible Newtonian fluid between parallel circular plates containing a single central air bubble in the inertial flow regime is presented in which a successive approximation technique is used to account for fluid inertia effects. A non-linear differential equation for the bubble radius is obtained and is solved by the Runge–Kutta Gill method and then the squeeze film force is determined. Approximate analytical solutions based on the perturbation method for a small amplitude of sinusoidal motion are derived for the air bubble radius and squeeze film force and are compared with numerical results. The combined effects of air bubble and fluid film inertia on the squeeze film force are investigated. The results by the present theory are compared with those obtained using modified lubrication theory. The inertia corrections in the maximum squeeze film force are analysed compared for both the methods for various values of the parameters that influence the motion.

Magnetohydrodynamic Squeeze Film Characteristics Between Parallel Circular Plates Containing a Single Central Air Bubble in the Inertial Flow Regime

In this paper, the magnetic effects on the Newtonian squeeze film between two circular parallel plates, containing a single central air bubble of cylindrical shape are theoretically investigated. A uniform magnetic field is applied perpendicular to the circular plates, which are in sinusoidal relative motion, and fluid film inertia effects are included in the analysis. Assuming an ideal gas under isothermal condition for an air bubble, a nonlinear differential equation for the bubble radius is obtained by approximating the momentum equation governing the magnetohydrodynamic squeeze film by the mean value averaged across the film thickness. Approximate analytical solutions for the air bubble radius, pressure distribution, and squeeze film force are determined by a perturbation method for small amplitude of sinusoidal motion and are compared with the numerical solution obtained by solving the nonlinear differential equation. The combined effects of air bubble, fluid film inertia, and magnetic field on the squeeze film force are analyzed.

The Velocity of Elastic P Waves in Unconsolidated Material Under Low Pressure

The growing interest in geophysical, and specifically seismic, methods to solve problems in engineering and environmental activities, calls for specific investigation into the elastic properties of unconsolidated materials lying in the uppermost part of the section. The study includes experimental measurement of the compressional velocity of soil, sand and gravel samples of different grain sizes, both dry and saturated. The wide range of velocity values obtained for saturated gravel samples required additional measurement runs, which were carried out every hour. The samples were jacketed into a hard rubber tube, which proved to be more convenient as its compressional velocity is less than that of the samples. The absolute error of measurement does not exceed 3.3%. The interpretation of the results led to the following conclusions: (1) the compressional velocity has a linear relationship with the logarithm of the pressure (semi‐logarithmic); (2) the effect of trapped air bubbles, 1–2% air saturation, significantly lowers the velocity of saturated sand samples below that of water; (3) grain packing has a more significant effect on p‐wave velocity for saturated samples than it does for dry samples; and (4) the propagation velocity may be used to estimate the porosity of the unconsolidated material, assuming the saturation and lithology are known.

Effect of macroscopic air bubbles on cell lysis by shock wave lithotripsy in vitro

In studies of cells or stones in vitro, the material to be exposed to shock waves (SWs) is commonly contained in plastic vials. It is difficult to remove all air bubbles from such vials. Because SWs reflect at an air–fluid interface, and because existing gas bubbles can serve as nuclei for cavitation events, we sought to determine in our system whether the inclusion of small, visible bubbles in the specimen vial has an effect on SW-induced cell lysis. We found that even small bubbles led to increased lysis of red blood cells (1- to 3-mm diameter bubbles, 9.8 ± 0.5% lysis, n = 7; no bubbles, 4.4 ± 0.8%, n = 4), and that the degree of lysis increased with bubble size. Damage could not be reduced by centrifuging the cells to the opposite end of the vial, away from the bubble. B-scan ultrasound imaging of blood in polypropylene pipette bulbs showed that, with each SW, bubbles were recruited from the air interface, mixing throughout the fluid volume, and these appeared to serve as nuclei for increased echogenicity during impact by subsequent SWs; thus, bubble effects in vials could involve the proliferation of cavitation nuclei from existing bubbles. Whereas injury to red blood cells was greatly increased by the presence of bubbles in vials, lytic injury to cultured epithelial cells (LLC-PK1, which have a more complex cytoarchitecture than red blood cells) was not increased by the presence of small air bubbles. This suggests different susceptibility to SW damage for different types of cells. Thus, the presence of even a small air bubble can increase SW-induced cell damage, perhaps by increasing the number of cavitation nuclei throughout the vial, but this effect is variable with cell type.

Bubble dynamics, shock waves and sonoluminescence

Sound and light emission by bubbles is studied experimentally. Single bubbles kept in a bubble trap and single lasergenerated bubbles are investigated using ultrafast and highspeed photography in c...

Rheology of bubble-bearing magmas

The physical effects of air or argon bubbles on the rheology of a calcium aluminosilicate melt have been measured at temperatures ranging from 830° to 960°C, at 1 bar pressure. The melt composition is SiO 2:64, Al 2O 3:23, and CaO:13 (wt%), while bubble volume fractions are: 0, 0.06, 0.13, 0.32, 0.41 and 0.47. Measured Newtonian viscosities range from 10 10 to 10 14 dPa s. Melts with bubble fractions of 0.06 and 0.13 show with increasing temperature ( T) an increasing relative viscosity for T < 850°C. However at T > 850°C, for all bubble fractions the viscosity decreases markedly with temperature. The observed maximum decrease of the relative viscosity is 75% for a bubble fraction of 0.47 at 907°C. At all bubble fractions the viscosity is independent of the applied stress, which ranged from 11 to 677 bars. No clear indications were observed of non-Newtonian rheological behavior. Under our experimental conditions the relative viscosity of the two phase liquid depends primarily on the bubble fraction. Physical and volcanological implications of these measurements are discussed.

The effect of air bubbles on the diffusion-controlled solidification of water and aqueous solutions of ammonium chloride

Gas pores appear during solidification when the gas concentration in the liquid is higher than the gas solubility at a certain location. Since the thermal conductivity of the gas can be orders of magnitude lower than that of the solid phases, the effective thermal conductivity of the porous solid may be lower when gas bubbles are present. In this study, experiments have been carried out to determine the effect of air bubbles on the process of solidification and solid formation. Water and ammonium chloride solutions have been solidified under diffusion controlled conditions and the temperature distributions as well as the interface positions have been measured during the experiments. The amount of dissolved air in the liquid was determined by controlling the pressure of the test cell, which was placed under a bell jar. The results of the experiments show that nucleation of air bubbles at the interface does not significantly affect the effective thermal conductivity of the solid. The results are supported using microscopic experimental observations of the bubble nucleation and growth.

Effect of Air Bubbles on Absorption of Solar Radiation by Water Droplets

It was suggested that absorption by a weakly absorbing droplet may be increased substantially by the presence of air bubbles within a droplet. The authors use an exact solution of the scattering of electromagnetic waves by a spherical particle containing an arbitrarily located spherical inclusion to investigate absorption of solar radiation by water droplets containing air bubbles. The presence of air bubbles within water droplets was found to have no significant effect on the absorption of solar radiation.

Laboratory and field assessment of an infrared turbidity probe and its response to particle size and variation in suspended sediment concentration

Abstract Using a combination of laboratory and field experiments, the performance of a Partech Instruments Ltd IR40-C active head suspended solids sensor has been tested with respect to changing particle size distribution and rapid variation in suspended sediment transport rate. The sensor, which utilizes light attenuation in the infrared waveband, has several advantages both over visible light optical designs and over nuclear or optical back-scatter (OBS) devices. Three sets of laboratory tests are reported: calibration experiments using estuarine, pro-glacial and control media; flume simulations of pulsed sediment supply at a variety of frequencies, concentrations and ambient flow velocities; and simple tests for the effect of air bubbles within the sensor light path. The sensor was also deployed in the field, together with an electromagnetic current meter, to monitor flow and suspended sediment transport fluctuations in the turbulent frequency range. Although the sensor performed well with respect to d...