3D bubble reconstruction using multiple cameras and space carving method

NASA Astrophysics Data System (ADS)

Fu, Yucheng; Liu, Yang

2018-07-01

An accurate measurement of bubble shape and size has a significant value in understanding the behavior of bubbles that exist in many engineering applications. Past studies usually use one or two cameras to estimate bubble volume, surface area, among other parameters. The 3D bubble shape and rotation angle are generally not available in these studies. To overcome this challenge and obtain more detailed information of individual bubbles, a 3D imaging system consisting of four high-speed cameras is developed in this paper, and the space carving method is used to reconstruct the 3D bubble shape based on the recorded high-speed images from different view angles. The proposed method can reconstruct the bubble surface with minimal assumptions. A benchmarking test is performed in a 3 cm  ×  1 cm rectangular channel with stagnant water. The results show that the newly proposed method can measure the bubble volume with an error of less than 2% compared with the syringe reading. The conventional two-camera system has an error around 10%. The one-camera system has an error greater than 25%. The visualization of a 3D bubble rising demonstrates the wall influence on bubble rotation angle and aspect ratio. This also explains the large error that exists in the single camera measurement.

Use of the Intradermal Tuberculin Test in a Herd of Captive Elk (Cervus elaphus nelsoni) Naturally Infected with Mycobacterium bovis

USDA-ARS?s Scientific Manuscript database

Tuberculosis of captive Cervidae, caused by Mycobacterium bovis, attracted attention in 1991 in the United States when investigations, prompted by the identification of a tuberculous elk (Cervus elaphus nelsoni) in Canada, revealed infected captive elk herds in 8 different states. Based on methods u...

Euthanasia of Cattle: Practical Considerations and Application.

PubMed

Shearer, Jan Keith

2018-04-17

Acceptable methods for the euthanasia of cattle include overdose of an anesthetic, gunshot and captive bolt. The use of anesthetics for euthanasia is costly and complicates carcass disposal. These issues can be avoided by use of a physical method such as gunshot or captive bolt; however, each requires that certain conditions be met to assure an immediate loss of consciousness and death. For example, the caliber of firearm and type of bullet are important considerations when gunshot is used. When captive bolt is used, a penetrating captive bolt loaded with the appropriate powder charge and accompanied by a follow up (adjunctive) step to assure death are required. The success of physical methods also requires careful selection of the anatomic site for entry of a “free bullet” or “bolt” in the case of penetrating captive bolt. Disease eradication plans for animal health emergencies necessitate methods of euthanasia that will facilitate rapid and efficient depopulation of animals while preserving their welfare to the greatest extent possible. A portable pneumatic captive bolt device has been developed and validated as effective for use in mass depopulation scenarios. Finally, while most tend to focus on the technical aspects of euthanasia, it is extremely important that no one forget the human cost for those who may be required to perform the task of euthanasia on a regular basis. Symptoms including depression, grief, sleeplessness and destructive behaviors including alcoholism and drug abuse are not uncommon for those who participate in the euthanasia of animals.

Simultaneous observation of cavitation bubbles generated in biological tissue by high-speed optical and acoustic imaging methods

NASA Astrophysics Data System (ADS)

Suzuki, Kai; Iwasaki, Ryosuke; Takagi, Ryo; Yoshizawa, Shin; Umemura, Shin-ichiro

2017-07-01

Acoustic cavitation bubbles are useful for enhancing the heating effect in high-intensity focused ultrasound (HIFU) treatment. Many studies were conducted to investigate the behavior of such bubbles in tissue-mimicking materials, such as a transparent gel phantom; however, the detailed behavior in tissue was still unclear owing to the difficulty in optical observation. In this study, a new biological phantom was developed to observe cavitation bubbles generated in an optically shallow area of tissue. Two imaging methods, high-speed photography using light scattering and high-speed ultrasonic imaging, were used for detecting the behavior of the bubbles simultaneously. The results agreed well with each other for the area of bubble formation and the temporal change in the region of bubbles, suggesting that both methods are useful for visualizing the bubbles.

Euthanasia of Cattle: Practical Considerations and Application

PubMed Central

Shearer, Jan Keith

2018-01-01

Simple Summary Methods recognized as acceptable for the euthanasia of cattle include overdose of an anesthetic, gunshot and captive bolt. The most common injectable anesthetic agent used for euthanasia is pentobarbital and while it may be the preferred method for euthanasia in sensitive situations, it creates significant challenges for disposal of animal remains. Gunshot and captive bolt are the more common methods used on farms and ranches because they are inexpensive, humane and do not complicate carcass disposal. Firearms must be of the proper caliber and loaded with the proper ammunition. Captive bolt, equipped with a penetrating bolt, is to be used on adult animals, whereas the non-penetrating (mushroom head) bolt should be reserved for use in calves (three months of age or less). In addition to selection of the proper firearm or captive bolt, successful euthanasia requires use of the proper anatomic site and adjunctive steps to assure death. The indicators of unconsciousness and death must be clearly understood and confirmed in all situations involving euthanasia. Tools for the efficient depopulation of a large feedlot, dairy or beef cattle operation as may be required in a national animal health emergency situation have been developed and validated as effective. Finally, the human impact of euthanasia cannot be underestimated. Symptoms of mental illness including depression, grief, sleeplessness and destructive behaviors including alcoholism and drug abuse are not uncommon for those who participate in the euthanasia of animals. Abstract Acceptable methods for the euthanasia of cattle include overdose of an anesthetic, gunshot and captive bolt. The use of anesthetics for euthanasia is costly and complicates carcass disposal. These issues can be avoided by use of a physical method such as gunshot or captive bolt; however, each requires that certain conditions be met to assure an immediate loss of consciousness and death. For example, the caliber of firearm and type of bullet are important considerations when gunshot is used. When captive bolt is used, a penetrating captive bolt loaded with the appropriate powder charge and accompanied by a follow up (adjunctive) step to assure death are required. The success of physical methods also requires careful selection of the anatomic site for entry of a “free bullet” or “bolt” in the case of penetrating captive bolt. Disease eradication plans for animal health emergencies necessitate methods of euthanasia that will facilitate rapid and efficient depopulation of animals while preserving their welfare to the greatest extent possible. A portable pneumatic captive bolt device has been developed and validated as effective for use in mass depopulation scenarios. Finally, while most tend to focus on the technical aspects of euthanasia, it is extremely important that no one forget the human cost for those who may be required to perform the task of euthanasia on a regular basis. Symptoms including depression, grief, sleeplessness and destructive behaviors including alcoholism and drug abuse are not uncommon for those who participate in the euthanasia of animals. PMID:29673140

A computationally efficient modelling of laminar separation bubbles

NASA Technical Reports Server (NTRS)

Maughmer, Mark D.

1988-01-01

The goal of this research is to accurately predict the characteristics of the laminar separation bubble and its effects on airfoil performance. To this end, a model of the bubble is under development and will be incorporated in the analysis section of the Eppler and Somers program. As a first step in this direction, an existing bubble model was inserted into the program. It was decided to address the problem of the short bubble before attempting the prediction of the long bubble. In the second place, an integral boundary-layer method is believed more desirable than a finite difference approach. While these two methods achieve similar prediction accuracy, finite-difference methods tend to involve significantly longer computer run times than the integral methods. Finally, as the boundary-layer analysis in the Eppler and Somers program employs the momentum and kinetic energy integral equations, a short-bubble model compatible with these equations is most preferable.

A bubble detection system for propellant filling pipeline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Wen; Zong, Guanghua; Bi, Shusheng

2014-06-15

This paper proposes a bubble detection system based on the ultrasound transmission method, mainly for probing high-speed bubbles in the satellite propellant filling pipeline. First, three common ultrasonic detection methods are compared and the ultrasound transmission method is used in this paper. Then, the ultrasound beam in a vertical pipe is investigated, suggesting that the width of the beam used for detection is usually smaller than the internal diameter of the pipe, which means that when bubbles move close to the pipe wall, they may escape from being detected. A special device is designed to solve this problem. It canmore » generate the spiral flow to force all the bubbles to ascend along the central line of the pipe. In the end, experiments are implemented to evaluate the performance of this system. Bubbles of five different sizes are generated and detected. Experiment results show that the sizes and quantity of bubbles can be estimated by this system. Also, the bubbles of different radii can be distinguished from each other. The numerical relationship between the ultrasound attenuation and the bubble radius is acquired and it can be utilized for estimating the unknown bubble size and measuring the total bubble volume.« less

Tooth wear in captive giraffes (Giraffa camelopardalis): mesowear analysis classifies free-ranging specimens as browsers but captive ones as grazers.

PubMed

Clauss, Marcus; Franz-Odendaal, Tamara A; Brasch, Juliane; Castell, Johanna C; Kaiser, Thomas

2007-09-01

Captive giraffe (Giraffa camelopardalis) mostly do not attain the longevity possible for this species and frequently have problems associated with low energy intake and fat storage mobilization. Abnormal tooth wear has been among the causes suggested as an underlying problem. This study utilizes a tooth wear scoring method ("mesowear") primarily used in paleobiology. This scoring method was applied to museum specimens of free-ranging (n=20) and captive (n=41) giraffes. The scoring system allows for the differentiation between attrition--(typical for browsers, as browse contains little abrasive silica) and abrasion--(typical for grazers, as grass contains abrasive silica) dominated tooth wear. The dental wear pattern of the free-ranging population is dominated by attrition, resembles that previously published for free-ranging giraffe, and clusters within browsing herbivores in comparative analysis. In contrast, the wear pattern of the captive population is dominated by abrasion and clusters among grazing herbivores in comparative analyses. A potential explanation for this difference in tooth wear is likely related to the content of abrasive elements in zoo diets. Silica content (measured as acid insoluble ash) is low in browse and alfalfa. However, grass hay and the majority of pelleted compound feeds contain higher amounts of silica. It can be speculated that the abnormal wear pattern in captivity compromises tooth function in captive giraffe, with deleterious long-term consequences.

A comparison of pedigree- and DNA-based measures for identifying inbreeding depression in the critically endangered Attwater's Prairie-chicken.

PubMed

Hammerly, Susan C; Morrow, Michael E; Johnson, Jeff A

2013-11-01

The primary goal of captive breeding programmes for endangered species is to prevent extinction, a component of which includes the preservation of genetic diversity and avoidance of inbreeding. This is typically accomplished by minimizing mean kinship in the population, thereby maintaining equal representation of the genetic founders used to initiate the captive population. If errors in the pedigree do exist, such an approach becomes less effective for minimizing inbreeding depression. In this study, both pedigree- and DNA-based methods were used to assess whether inbreeding depression existed in the captive population of the critically endangered Attwater's Prairie-chicken (Tympanuchus cupido attwateri), a subspecies of prairie grouse that has experienced a significant decline in abundance and concurrent reduction in neutral genetic diversity. When examining the captive population for signs of inbreeding, variation in pedigree-based inbreeding coefficients (f(pedigree)) was less than that obtained from DNA-based methods (f(DNA)). Mortality of chicks and adults in captivity were also positively correlated with parental relatedness (r(DNA)) and f(DNA), respectively, while no correlation was observed with pedigree-based measures when controlling for additional variables such as age, breeding facility, gender and captive/release status. Further, individual homozygosity by loci (HL) and parental rDNA values were positively correlated with adult mortality in captivity and the occurrence of a lethal congenital defect in chicks, respectively, suggesting that inbreeding may be a contributing factor increasing the frequency of this condition among Attwater's Prairie-chickens. This study highlights the importance of using DNA-based methods to better inform management decisions when pedigrees are incomplete or errors may exist due to uncertainty in pairings. © 2013 John Wiley & Sons Ltd.

Monitoring and analyzing waste glass compositions

DOEpatents

Schumacher, R.F.

1994-03-01

A device and method are described for determining the viscosity of a fluid, preferably molten glass. The apparatus and method use the velocity of rising bubbles, preferably helium bubbles, within the molten glass to determine the viscosity of the molten glass. The bubbles are released from a tube positioned below the surface of the molten glass so that the bubbles pass successively between two sets of electrodes, one above the other, that are continuously monitoring the conductivity of the molten glass. The measured conductivity will change as a bubble passes between the electrodes enabling an accurate determination of when a bubble has passed between the electrodes. The velocity of rising bubbles can be determined from the time interval between a change in conductivity of the first electrode pair and the second, upper electrode pair. The velocity of the rise of the bubbles in the glass melt is used in conjunction with other physical characteristics, obtained by known methods, to determine the viscosity of the glass melt fluid and, hence, glass quality. 2 figures.

Monitoring and analyzing waste glass compositions

DOEpatents

Schumacher, Ray F.

1994-01-01

A device and method for determining the viscosity of a fluid, preferably molten glass. The apparatus and method uses the velocity of rising bubbles, preferably helium bubbles, within the molten glass to determine the viscosity of the molten glass. The bubbles are released from a tube positioned below the surface of the molten glass so that the bubbles pass successively between two sets of electrodes, one above the other, that are continuously monitoring the conductivity of the molten glass. The measured conductivity will change as a bubble passes between the electrodes enabling an accurate determination of when a bubble has passed between the electrodes. The velocity of rising bubbles can be determined from the time interval between a change in conductivity of the first electrode pair and the second, upper electrode pair. The velocity of the rise of the bubbles in the glass melt is used in conjunction with other physical characteristics, obtained by known methods, to determine the viscosity of the glass melt fluid and, hence, glass quality.

A mathematical definition of the financial bubbles and crashes

NASA Astrophysics Data System (ADS)

Watanabe, Kota; Takayasu, Hideki; Takayasu, Misako

2007-09-01

We check the validity of the mathematical method of detecting financial bubbles or crashes, which is based on a data fitting with an exponential function. We show that the period of a bubble can be determined nearly uniquely independent of the precision of data. The method is widely applicable for stock market data such as the Internet bubble.

Comparison of Pore-scale CO2-water-glass System Wettability and Conventional Wettability Measurement on a Flat Plate for Geological CO2 Sequestration

NASA Astrophysics Data System (ADS)

Jafari, M.; Cao, S. C.; Jung, J.

2017-12-01

Goelogical CO2 sequestration (GCS) has been recently introduced as an effective method to mitigate carbon dioxide emission. CO2 from main producer sources is collected and then is injected underground formations layers to be stored for thousands to millions years. A safe and economical storage project depends on having an insight of trapping mechanisms, fluids dynamics, and interaction of fluids-rocks. Among different forces governing fluids mobility and distribution in GCS condition, capillary pressure is of importance, which, in turn, wettability (measured by contact angel (CA)) is the most controversial parameters affecting it. To explore the sources of discrepancy in the literature for CA measurement, we conducted a series of conventional captive bubble test on glass plates under high pressure condition. By introducing a shape factor, we concluded that surface imperfection can distort the results in such tests. Since the conventional methods of measuring the CA is affected by gravity and scale effect, we introduced a different technique to measure pore-scale CA inside a transparent glass microchip. Our method has the ability to consider pore sizes and simulate static and dynamics CA during dewetting and imbibition. Glass plates shows a water-wet behavior (CA 30° - 45°) by a conventional experiment consistent with literature. However, CA of miniature bubbles inside of the micromodel can have a weaker water-wet behavior (CA 55° - 69°). In a more realistic pore-scale condition, water- CO2 interface covers whole width of a pore throats. Under this condition, the receding CA, which is used for injectability and capillary breakthrough pressure, increases with decreasing pores size. On the other hand, advancing CA, which is important for residual or capillary trapping, does not show a correlation with throat sizes. Static CA measured in the pores during dewetting is lower than static CA on flat plate, but it is much higher when measured during imbibition implying weaker water-wet behavior. Pore-scale CA, which realistically represents rocks wettability behavior, shows weaker water-wet behavior than conventional measurement methods, which must be considered for safety of geological storage.

Efficient gene transfection to the brain with ultrasound irradiation in mice using stabilized bubble lipopolyplexes prepared by the surface charge regulation method.

PubMed

Ogawa, Koki; Fuchigami, Yuki; Hagimori, Masayori; Fumoto, Shintaro; Miura, Yusuke; Kawakami, Shigeru

2018-01-01

We previously developed anionic ternary bubble lipopolyplexes, an ultrasound-responsive carrier, expecting safe and efficient gene transfection. However, bubble lipopolyplexes have a low capacity for echo gas (C 3 F 8 ) encapsulation (EGE) in nonionic solution such as 5% glucose. On the other hand, we were able to prepare bubble lipopolyplexes by inserting phosphate-buffered saline before C 3 F 8 encapsulation. Surface charge regulation (SCR) by electrolytes stabilizes liposome/plasmid DNA (pDNA) complexes by accelerated membrane fusion. Considering these facts, we hypothesized that SCR by electrolytes such as NaCl would promote C 3 F 8 encapsulation in bubble lipopolyplexes mediated by accelerated membrane fusion. We defined this hypothesis as SCR-based EGE (SCR-EGE). Bubble lipopolyplexes prepared by the SCR-EGE method (SCR-EGE bubble lipopolyplexes) are expected to facilitate the gene transfection because of the high amount of C 3 F 8 . Therefore, we applied these methods for gene delivery to the brain and evaluated the characteristics of transgene expression in the brain. First, we measured the encapsulation efficiency of C 3 F 8 in SCR-EGE bubble lipopolyplexes. Next, we applied these bubble lipopolyplexes to the mouse brain; then, we evaluated the transfection efficiency. Furthermore, three-dimensional transgene distribution was observed using multicolor deep imaging. SCR-EGE bubble lipopolyplexes had a higher C 3 F 8 content than conventional bubble lipopolyplexes. In terms of safety, SCR-EGE bubble lipopolyplexes possessed an anionic potential and showed no aggregation with erythrocytes. After applying SCR-EGE bubble lipopolyplexes to the brain, high transgene expression was observed by combining with ultrasound irradiation. As a result, transgene expression mediated by SCR-EGE bubble lipopolyplexes was observed mainly on blood vessels and partially outside of blood vessels. The SCR-EGE method may promote C 3 F 8 encapsulation in bubble lipopolyplexes, and SCR-EGE bubble lipopolyplexes may be potent carriers for efficient and safe gene transfection in the brain, especially to the blood vessels.

Removal of hydrogen bubbles from nuclear reactors

NASA Technical Reports Server (NTRS)

Jenkins, R. V.

1980-01-01

Method proposed for removing large hydrogen bubbles from nuclear environment uses, in its simplest form, hollow spheres of palladium or platinum. Methods would result in hydrogen bubble being reduced in size without letting more radioactivity outside reactor.

Numerical simulation of bubble deformation in magnetic fluids by finite volume method

NASA Astrophysics Data System (ADS)

Yamasaki, Haruhiko; Yamaguchi, Hiroshi

2017-06-01

Bubble deformation in magnetic fluids under magnetic field is investigated numerically by an interface capturing method. The numerical method consists of a coupled level-set and VOF (Volume of Fluid) method, combined with conservation CIP (Constrained Interpolation Profile) method with the self-correcting procedure. In the present study considering actual physical properties of magnetic fluid, bubble deformation under given uniform magnetic field is analyzed for internal magnetic field passing through a magnetic gaseous and liquid phase interface. The numerical results explain the mechanism of bubble deformation under presence of given magnetic field.

Diffuse interface simulation of bubble rising process: a comparison of adaptive mesh refinement and arbitrary lagrange-euler methods

NASA Astrophysics Data System (ADS)

Wang, Ye; Cai, Jiejin; Li, Qiong; Yin, Huaqiang; Yang, Xingtuan

2018-06-01

Gas-liquid two phase flow exists in several industrial processes and light-water reactors (LWRs). A diffuse interface based finite element method with two different mesh generation methods namely, the Adaptive Mesh Refinement (AMR) and the Arbitrary Lagrange Euler (ALE) methods is used to model the shape and velocity changes in a rising bubble. Moreover, the calculating speed and mesh generation strategies of AMR and ALE are contrasted. The simulation results agree with the Bhagat's experiments, indicating that both mesh generation methods can simulate the characteristics of bubble accurately. We concluded that: the small bubble rises as elliptical with oscillation, whereas a larger bubble (11 mm > d > 7 mm) rises with a morphology between the elliptical and cap type with a larger oscillation. When the bubble is large (d > 11 mm), it rises up as a cap type, and the amplitude becomes smaller. Moreover, it takes longer to achieve the stable shape from the ellipsoid to the spherical cap type with the increase of the bubble diameter. The results also show that for smaller diameter case, the ALE method uses fewer grids and has a faster calculation speed, but the AMR method can solve the case of a large geometry deformation efficiently.

Comparison of cavitation bubbles evolution in viscous media

NASA Astrophysics Data System (ADS)

Jasikova, Darina; Schovanec, Petr; Kotek, Michal; Kopecky, Vaclav

2018-06-01

There have been tried many types of liquids with different ranges of viscosity values that have been tested to form a single cavitation bubble. The purpose of these experiments was to observe the behaviour of cavitation bubbles in media with different ranges of absorbance. The most of the method was based on spark to induced superheat limit of liquid. Here we used arrangement of the laser-induced breakdown (LIB) method. There were described the set cavitation setting that affects the size bubble in media with different absorbance. We visualized the cavitation bubble with a 60 kHz high speed camera. We used here shadowgraphy setup for the bubble visualization. There were observed time development and bubble extinction in various media, where the size of the bubble in the silicone oil was extremely small, due to the absorbance size of silicon oil.

Nonlinear Bubble Dynamics And The Effects On Propagation Through Near-Surface Bubble Layers

NASA Astrophysics Data System (ADS)

Leighton, Timothy G.

2004-11-01

Nonlinear bubble dynamics are often viewed as the unfortunate consequence of having to use high acoustic pressure amplitudes when the void fraction in the near-surface oceanic bubble layer is great enough to cause severe attenuation (e.g. >50 dB/m). This is seen as unfortunate since existing models for acoustic propagation in bubbly liquids are based on linear bubble dynamics. However, the development of nonlinear models does more than just allow quantification of the errors associated with the use of linear models. It also offers the possibility of propagation modeling and acoustic inversions which appropriately incorporate the bubble nonlinearity. Furthermore, it allows exploration and quantification of possible nonlinear effects which may be exploited. As a result, high acoustic pressure amplitudes may be desirable even in low void fractions, because they offer opportunities to gain information about the bubble cloud from the nonlinearities, and options to exploit the nonlinearities to enhance communication and sonar in bubbly waters. This paper presents a method for calculating the nonlinear acoustic cross-sections, scatter, attenuations and sound speeds from bubble clouds which may be inhomogeneous. The method allows prediction of the time dependency of these quantities, both because the cloud may vary and because the incident acoustic pulse may have finite and arbitrary time history. The method can be readily adapted for bubbles in other environments (e.g. clouds of interacting bubbles, sediments, structures, in vivo, reverberant conditions etc.). The possible exploitation of bubble acoustics by marine mammals, and for sonar enhancement, is explored.

Captive-rearing of Gunnison sage-grouse from egg collection to adulthood to foster proactive conservation and recovery of a conservation-reliant species.

PubMed

Apa, Anthony D; Wiechman, Lief A

2015-01-01

Gunnison sage-grouse (Centrocercus minimus) are distributed across southwestern Colorado and southeastern Utah, United States. Their distribution has decreased over the past century and the species has been listed as threatened by the U.S. Fish and Wildlife Service. Reduced genetic diversity, small population size, and isolation may affect Gunnison sage-grouse population persistence. Population augmentation can be used to counteract or mitigate these issues, but traditional translocation efforts have yielded mixed, and mostly unsuccessful, results. Captive-rearing is a viable, although much debated, conservation approach to bolster wild conservation-reliant species. Although there have been captive-rearing efforts with greater sage-grouse (C. urophasianus), to date, no information exists about captive-rearing methods for Gunnison sage-grouse. Therefore, we investigated techniques for egg collection, artificial incubation, hatch, and captive-rearing of chicks, juveniles, subadults, and adults for Gunnison sage-grouse. In 2009 we established a captive flock that produced viable eggs. From 2009-2011, we collected and artificially incubated 206 Gunnison sage-grouse eggs from 23 wild and 14 captive females. Our hatchability was 90%. Wild-produced eggs were heavier than captive-produced eggs and lost mass similarly during incubation. We produced 148 chicks in captivity and fed them a variety of food sources (e.g. invertebrates to commercial chow). Bacterial infections were the primary cause of chick mortality, but we successfully reduced the overall mortality rate during the course of our study. Conservationists and managers should consider the utility in developing a captive-rearing program or creating a captive population as part of a proactive conservation effort for the conservation-reliant Gunnison sage-grouse. © 2015 Wiley Periodicals, Inc.

Bubble structure evaluation method of sponge cake by using image morphology

NASA Astrophysics Data System (ADS)

Kato, Kunihito; Yamamoto, Kazuhiko; Nonaka, Masahiko; Katsuta, Yukiyo; Kasamatsu, Chinatsu

2007-01-01

Nowadays, many evaluation methods for food industry by using image processing are proposed. These methods are becoming new evaluation method besides the sensory test and the solid-state measurement that have been used for the quality evaluation recently. The goal of our research is structure evaluation of sponge cake by using the image processing. In this paper, we propose a feature extraction method of the bobble structure in the sponge cake. Analysis of the bubble structure is one of the important properties to understand characteristics of the cake from the image. In order to take the cake image, first we cut cakes and measured that's surface by using the CIS scanner, because the depth of field of this type scanner is very shallow. Therefore the bubble region of the surface has low gray scale value, and it has a feature that is blur. We extracted bubble regions from the surface images based on these features. The input image is binarized, and the feature of bubble is extracted by the morphology analysis. In order to evaluate the result of feature extraction, we compared correlation with "Size of the bubble" of the sensory test result. From a result, the bubble extraction by using morphology analysis gives good correlation. It is shown that our method is as well as the subjectivity evaluation.

Numerical simulation of superheated vapor bubble rising in stagnant liquid

NASA Astrophysics Data System (ADS)

Samkhaniani, N.; Ansari, M. R.

2017-09-01

In present study, the rising of superheated vapor bubble in saturated liquid is simulated using volume of fluid method in OpenFOAM cfd package. The surface tension between vapor-liquid phases is considered using continuous surface force method. In order to reduce spurious current near interface, Lafaurie smoothing filter is applied to improve curvature calculation. Phase change is considered using Tanasawa mass transfer model. The variation of saturation temperature in vapor bubble with local pressure is considered with simplified Clausius-Clapeyron relation. The couple velocity-pressure equation is solved using PISO algorithm. The numerical model is validated with: (1) isothermal bubble rising and (2) one-dimensional horizontal film condensation. Then, the shape and life time history of single superheated vapor bubble are investigated. The present numerical study shows vapor bubble in saturated liquid undergoes boiling and condensation. It indicates bubble life time is nearly linear proportional with bubble size and superheat temperature.

Acoustic measurement of bubble size in an inkjet printhead.

PubMed

Jeurissen, Roger; van der Bos, Arjan; Reinten, Hans; van den Berg, Marc; Wijshoff, Herman; de Jong, Jos; Versluis, Michel; Lohse, Detlef

2009-11-01

The volume of a bubble in a piezoinkjet printhead is measured acoustically. The method is based on a numerical model of the investigated system. The piezo not only drives the system but it is also used as a sensor by measuring the current it generates. The numerical model is used to predict this current for a given bubble volume. The inverse problem is to infer the bubble volume from an experimentally obtained piezocurrent. By solving this inverse problem, the size and position of the bubble can thus be measured acoustically. The method is experimentally validated with an inkjet printhead that is augmented with a glass connection channel, through which the bubble was observed optically, while at the same time the piezocurrent was measured. The results from the acoustical measurement method correspond closely to the results from the optical measurement.

Bubble measuring instrument and method

NASA Technical Reports Server (NTRS)

Magari, Patrick J. (Inventor); Kline-Schoder, Robert (Inventor)

2003-01-01

Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer, respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.

Bubble Measuring Instrument and Method

NASA Technical Reports Server (NTRS)

Kline-Schoder, Robert (Inventor); Magari, Patrick J. (Inventor)

2002-01-01

Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer. respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.

9 CFR 77.20 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TUBERCULOSIS Captive Cervids... “Uniform Methods and Rules—Bovine Tuberculosis Eradication” and in which tuberculosis is prevalent in less.... A herd of captive cervids that has tested negative to at least two consecutive official tuberculosis...

9 CFR 77.20 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TUBERCULOSIS Captive Cervids... “Uniform Methods and Rules—Bovine Tuberculosis Eradication” and in which tuberculosis is prevalent in less.... A herd of captive cervids that has tested negative to at least two consecutive official tuberculosis...

9 CFR 77.20 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TUBERCULOSIS Captive Cervids... “Uniform Methods and Rules—Bovine Tuberculosis Eradication” and in which tuberculosis is prevalent in less.... A herd of captive cervids that has tested negative to at least two consecutive official tuberculosis...

9 CFR 77.20 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TUBERCULOSIS Captive Cervids... “Uniform Methods and Rules—Bovine Tuberculosis Eradication” and in which tuberculosis is prevalent in less.... A herd of captive cervids that has tested negative to at least two consecutive official tuberculosis...

9 CFR 77.20 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TUBERCULOSIS Captive Cervids... “Uniform Methods and Rules—Bovine Tuberculosis Eradication” and in which tuberculosis is prevalent in less.... A herd of captive cervids that has tested negative to at least two consecutive official tuberculosis...

Modelling cavitation erosion using fluid–material interaction simulations

PubMed Central

Chahine, Georges L.; Hsiao, Chao-Tsung

2015-01-01

Material deformation and pitting from cavitation bubble collapse is investigated using fluid and material dynamics and their interaction. In the fluid, a novel hybrid approach, which links a boundary element method and a compressible finite difference method, is used to capture non-spherical bubble dynamics and resulting liquid pressures efficiently and accurately. The bubble dynamics is intimately coupled with a finite-element structure model to enable fluid/structure interaction simulations. Bubble collapse loads the material with high impulsive pressures, which result from shock waves and bubble re-entrant jet direct impact on the material surface. The shock wave loading can be from the re-entrant jet impact on the opposite side of the bubble, the fast primary collapse of the bubble, and/or the collapse of the remaining bubble ring. This produces high stress waves, which propagate inside the material, cause deformation, and eventually failure. A permanent deformation or pit is formed when the local equivalent stresses exceed the material yield stress. The pressure loading depends on bubble dynamics parameters such as the size of the bubble at its maximum volume, the bubble standoff distance from the material wall and the pressure driving the bubble collapse. The effects of standoff and material type on the pressure loading and resulting pit formation are highlighted and the effects of bubble interaction on pressure loading and material deformation are preliminarily discussed. PMID:26442140

A numerical method for the dynamics of non-spherical cavitation bubbles

NASA Technical Reports Server (NTRS)

Lucca, G.; Prosperetti, A.

1982-01-01

A boundary integral numerical method for the dynamics of nonspherical cavitation bubbles in inviscid incompressible liquids is described. Only surface values of the velocity potential and its first derivatives are involved. The problem of solving the Laplace equation in the entire domain occupied by the liquid is thus avoided. The collapse of a bubble in the vicinity of a solid wall and the collapse of three bubbles with collinear centers are considered.

Adhesion of bubbles and drops to solid surfaces, and anisotropic surface tensions studied by capillary meniscus dynamometry.

PubMed

Danov, Krassimir D; Stanimirova, Rumyana D; Kralchevsky, Peter A; Marinova, Krastanka G; Stoyanov, Simeon D; Blijdenstein, Theodorus B J; Cox, Andrew R; Pelan, Eddie G

2016-07-01

Here, we review the principle and applications of two recently developed methods: the capillary meniscus dynamometry (CMD) for measuring the surface tension of bubbles/drops, and the capillary bridge dynamometry (CBD) for quantifying the bubble/drop adhesion to solid surfaces. Both methods are based on a new data analysis protocol, which allows one to decouple the two components of non-isotropic surface tension. For an axisymmetric non-fluid interface (e.g. bubble or drop covered by a protein adsorption layer with shear elasticity), the CMD determines the two different components of the anisotropic surface tension, σs and σφ, which are acting along the "meridians" and "parallels", and vary throughout the interface. The method uses data for the instantaneous bubble (drop) profile and capillary pressure, but the procedure for data processing is essentially different from that of the conventional drop shape analysis (DSA) method. In the case of bubble or drop pressed against a substrate, which forms a capillary bridge, the CBD method allows one to determine also the capillary-bridge force for both isotropic (fluid) and anisotropic (solidified) adsorption layers. The experiments on bubble (drop) detachment from the substrate show the existence of a maximal pulling force, Fmax, that can be resisted by an adherent fluid particle. Fmax can be used to quantify the strength of adhesion of bubbles and drops to solid surfaces. Its value is determined by a competition of attractive transversal tension and repulsive disjoining pressure forces. The greatest Fmax values have been measured for bubbles adherent to glass substrates in pea-protein solutions. The bubble/wall adhesion is lower in solutions containing the protein HFBII hydrophobin, which could be explained with the effect of sandwiched protein aggregates. The applicability of the CBD method to emulsion systems is illustrated by experiments with soybean-oil drops adherent to hydrophilic and hydrophobic substrates in egg yolk solutions. The results reveal how the interfacial rigidity, as well as the bubble/wall and drop/wall adhesion forces, can be quantified and controlled in relation to optimizing the properties of foams and emulsions. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantitative evaluation method of the bubble structure of sponge cake by using morphology image processing

NASA Astrophysics Data System (ADS)

Tatebe, Hironobu; Kato, Kunihito; Yamamoto, Kazuhiko; Katsuta, Yukio; Nonaka, Masahiko

2005-12-01

Now a day, many evaluation methods for the food industry by using image processing are proposed. These methods are becoming new evaluation method besides the sensory test and the solid-state measurement that are using for the quality evaluation. An advantage of the image processing is to be able to evaluate objectively. The goal of our research is structure evaluation of sponge cake by using image processing. In this paper, we propose a feature extraction method of the bobble structure in the sponge cake. Analysis of the bubble structure is one of the important properties to understand characteristics of the cake from the image. In order to take the cake image, first we cut cakes and measured that's surface by using the CIS scanner. Because the depth of field of this type scanner is very shallow, the bubble region of the surface has low gray scale values, and it has a feature that is blur. We extracted bubble regions from the surface images based on these features. First, input image is binarized, and the feature of bubble is extracted by the morphology analysis. In order to evaluate the result of feature extraction, we compared correlation with "Size of the bubble" of the sensory test result. From a result, the bubble extraction by using morphology analysis gives good correlation. It is shown that our method is as well as the subjectivity evaluation.

A theoretical method for selecting space craft and space suit atmospheres.

PubMed

Vann, R D; Torre-Bueno, J R

1984-12-01

A theoretical method for selecting space craft and space suit atmospheres assumes that gas bubbles cause decompression sickness and that the risk increases when a critical bubble volume is exceeded. The method is consistent with empirical decompression exposures for humans under conditions of nitrogen equilibrium between the lungs and tissues. Space station atmospheres are selected so that flight crews may decompress immediately from sea level to station pressure without preoxygenation. Bubbles form as a result of this decompression but are less than the critical volume. The bubbles are absorbed during an equilibration period after which immediate transition to suit pressure is possible. Exercise after decompression and incomplete nitrogen equilibrium are shown to increase bubble size, and limit the usefulness of one previously tested stage decompression procedure for the Shuttle. The method might be helpful for evaluating decompression procedures before testing.

Social grooming network in captive chimpanzees: does the wild or captive origin of group members affect sociality?

PubMed

Levé, Marine; Sueur, Cédric; Petit, Odile; Matsuzawa, Tetsuro; Hirata, Satoshi

2016-01-01

Many chimpanzees throughout the world are housed in captivity, and there is an increasing effort to recreate social groups by mixing individuals with captive origins with those with wild origins. Captive origins may entail restricted rearing conditions during early infant life, including, for example, no maternal rearing and a limited social life. Early rearing conditions have been linked with differences in tool-use behavior between captive- and wild-born chimpanzees. If physical cognition can be impaired by non-natural rearing, what might be the consequences for social capacities? This study describes the results of network analysis based on grooming interactions in chimpanzees with wild and captive origins living in the Kumamoto Sanctuary in Kumamoto, Japan. Grooming is a complex social activity occupying up to 25% of chimpanzees' waking hours and plays a role in the emergence and maintenance of social relationships. We assessed whether the social centralities and roles of chimpanzees might be affected by their origin (captive vs wild). We found that captive- and wild-origin chimpanzees did not differ in their grooming behavior, but that theoretical removal of individuals from the network had differing impacts depending on the origin of the individual. Contrary to findings that non-natural early rearing has long-term effects on physical cognition, living in social groups seems to compensate for the negative effects of non-natural early rearing. Social network analysis (SNA) and, in particular, theoretical removal analysis, were able to highlight differences between individuals that would have been impossible to show using classical methods. The social environment of captive animals is important to their well-being, and we are only beginning to understand how SNA might help to enhance animal welfare.

Interaction of lithotripter shockwaves with single inertial cavitation bubbles

PubMed Central

Klaseboer, Evert; Fong, Siew Wan; Turangan, Cary K.; Khoo, Boo Cheong; Szeri, Andrew J.; Calvisi, Michael L.; Sankin, Georgy N.; Zhong, Pei

2008-01-01

The dynamic interaction of a shockwave (modelled as a pressure pulse) with an initially spherically oscillating bubble is investigated. Upon the shockwave impact, the bubble deforms non-spherically and the flow field surrounding the bubble is determined with potential flow theory using the boundary-element method (BEM). The primary advantage of this method is its computational efficiency. The simulation process is repeated until the two opposite sides of the bubble surface collide with each other (i.e. the formation of a jet along the shockwave propagation direction). The collapse time of the bubble, its shape and the velocity of the jet are calculated. Moreover, the impact pressure is estimated based on water-hammer pressure theory. The Kelvin impulse, kinetic energy and bubble displacement (all at the moment of jet impact) are also determined. Overall, the simulated results compare favourably with experimental observations of lithotripter shockwave interaction with single bubbles (using laser-induced bubbles at various oscillation stages). The simulations confirm the experimental observation that the most intense collapse, with the highest jet velocity and impact pressure, occurs for bubbles with intermediate size during the contraction phase when the collapse time of the bubble is approximately equal to the compressive pulse duration of the shock wave. Under this condition, the maximum amount of energy of the incident shockwave is transferred to the collapsing bubble. Further, the effect of the bubble contents (ideal gas with different initial pressures) and the initial conditions of the bubble (initially oscillating vs. non-oscillating) on the dynamics of the shockwave–bubble interaction are discussed. PMID:19018296

Interaction of lithotripter shockwaves with single inertial cavitation bubbles.

PubMed

Klaseboer, Evert; Fong, Siew Wan; Turangan, Cary K; Khoo, Boo Cheong; Szeri, Andrew J; Calvisi, Michael L; Sankin, Georgy N; Zhong, Pei

2007-01-01

The dynamic interaction of a shockwave (modelled as a pressure pulse) with an initially spherically oscillating bubble is investigated. Upon the shockwave impact, the bubble deforms non-spherically and the flow field surrounding the bubble is determined with potential flow theory using the boundary-element method (BEM). The primary advantage of this method is its computational efficiency. The simulation process is repeated until the two opposite sides of the bubble surface collide with each other (i.e. the formation of a jet along the shockwave propagation direction). The collapse time of the bubble, its shape and the velocity of the jet are calculated. Moreover, the impact pressure is estimated based on water-hammer pressure theory. The Kelvin impulse, kinetic energy and bubble displacement (all at the moment of jet impact) are also determined. Overall, the simulated results compare favourably with experimental observations of lithotripter shockwave interaction with single bubbles (using laser-induced bubbles at various oscillation stages). The simulations confirm the experimental observation that the most intense collapse, with the highest jet velocity and impact pressure, occurs for bubbles with intermediate size during the contraction phase when the collapse time of the bubble is approximately equal to the compressive pulse duration of the shock wave. Under this condition, the maximum amount of energy of the incident shockwave is transferred to the collapsing bubble. Further, the effect of the bubble contents (ideal gas with different initial pressures) and the initial conditions of the bubble (initially oscillating vs. non-oscillating) on the dynamics of the shockwave-bubble interaction are discussed.

Illegal captive lemurs in Madagascar: Comparing the use of online and in-person data collection methods.

PubMed

Reuter, Kim E; Schaefer, Melissa S

2017-11-01

Although it is illegal to capture, sell, and trade lemurs, the live capture of lemurs in Madagascar is ongoing and may have impacted over 28,000 lemurs between 2010 and 2013. Only one study has examined this trade and did so using in-person interviews in northern Madagascar. The current study sought to expand this existing dataset and examine the comparability of online surveys to more traditional on-location data collection methods. In this study, we collected data through a web-based survey resulting in 302 sightings of 685 captive lemurs. We also collected data from 171 hotel and 43 restaurant websites and social media profiles. Survey submissions included sightings of 30 species from 10 genera, nearly twice as many species as identified via the in-person interviews. Lemur catta, Varecia variegata, and Eulemur fulvus were the most common species sighted in captivity. Captive lemurs were reported in 19 of Madagascar's 22 administrative regions and most were seen in urban areas near their habitat ranges. This represents a wider geographic distribution of captive lemurs than previously found through in-person interviews. The online survey results were broadly similar to those of the in-person surveys though greater in species and geographic diversity demonstrating advantages to the use of online surveys. The online research methods were low in cost (USD $100) compared to on-location data collection (USD $12,000). Identified disadvantages included sample bias; most of the respondents to the online survey were researchers and many captive sightings were near study sites. The results illustrate the benefits of incorporating a social science approach using online surveys as a complement to traditional fieldwork. Am. J. Primatol. 79:e22541, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Magnetic Bubble Memories for Data Collection in Sounding Rockets,

DTIC Science & Technology

1982-01-29

generate interest in bubbles as a mass storage device for micro - processor based equipment, manufacturers have come up with a variety of diversified...absence of a bubble represents a Ŕ". With diameters on the order of I to 5 micro -meters, these bubbles are so small that extremely tiny chips can hold...methods of transfer: polled I/O, interrupt driven I/O, and direct memory access (DMA). The first two methods require tho host processor be involved

Magnetic skyrmion bubble motion driven by surface acoustic waves

DOE PAGES

Nepal, Rabindra; Güngördü, Utkan; Kovalev, Alexey A.

2018-03-12

Here, we study the dynamical control of a magnetic skyrmion bubble by using counter-propagating surface acoustic waves (SAWs) in a ferromagnet. First, we determine the bubble mass and derive the force due to SAWs acting on a magnetic bubble using Thiele’s method. The force that pushes the bubble is proportional to the strain gradient for the major strain component. We then study the dynamical pinning and motion of magnetic bubbles by SAWs in a nanowire. In a disk geometry, we propose a SAWs-driven skyrmion bubble oscillator with two resonant frequencies.

Magnetic skyrmion bubble motion driven by surface acoustic waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nepal, Rabindra; Güngördü, Utkan; Kovalev, Alexey A.

Here, we study the dynamical control of a magnetic skyrmion bubble by using counter-propagating surface acoustic waves (SAWs) in a ferromagnet. First, we determine the bubble mass and derive the force due to SAWs acting on a magnetic bubble using Thiele’s method. The force that pushes the bubble is proportional to the strain gradient for the major strain component. We then study the dynamical pinning and motion of magnetic bubbles by SAWs in a nanowire. In a disk geometry, we propose a SAWs-driven skyrmion bubble oscillator with two resonant frequencies.

Trapping of a micro-bubble by non-paraxial Gaussian beam: computation using the FDTD method.

PubMed

Sung, Seung-Yong; Lee, Yong-Gu

2008-03-03

Optical forces on a micro-bubble were computed using the Finite Difference Time Domain method. Non-paraxial Gaussian beam equation was used to represent the incident laser with high numerical aperture, common in optical tweezers. The electromagnetic field distribution around a micro-bubble was computed using FDTD method and the electromagnetic stress tensor on the surface of a micro-bubble was used to compute the optical forces. By the analysis of the computational results, interesting relations between the radius of the circular trapping ring and the corresponding stability of the trap were found.

Numerical simulation of single bubble dynamics under acoustic travelling waves.

PubMed

Ma, Xiaojian; Huang, Biao; Li, Yikai; Chang, Qing; Qiu, Sicong; Su, Zheng; Fu, Xiaoying; Wang, Guoyu

2018-04-01

The objective of this paper is to apply CLSVOF method to investigate the single bubble dynamics in acoustic travelling waves. The Naiver-Stokes equation considering the acoustic radiation force is proposed and validated to capture the bubble behaviors. And the CLSVOF method, which can capture the continuous geometric properties and satisfies mass conservation, is applied in present work. Firstly, the regime map, depending on the dimensionless acoustic pressure amplitude and acoustic wave number, is constructed to present different bubble behaviors. Then, the time evolution of the bubble oscillation is investigated and analyzed. Finally, the effect of the direction and the damping coefficient of acoustic wave propagation on the bubble behavior are also considered. The numerical results show that the bubble presents distinct oscillation types in acoustic travelling waves, namely, volume oscillation, shape oscillation, and splitting oscillation. For the splitting oscillation, the formation of jet, splitting of bubble, and the rebound of sub-bubbles may lead to substantial increase in pressure fluctuations on the boundary. For the shape oscillation, the nodes and antinodes of the acoustic pressure wave contribute to the formation of the "cross shape" of the bubble. It should be noted that the direction of the bubble translation and bubble jet are always towards the direction of wave propagation. In addition, the damping coefficient causes bubble in shape oscillation to be of asymmetry in shape and inequality in size, and delays the splitting process. Copyright © 2017 Elsevier B.V. All rights reserved.

Cryosurgery Planning Using Bubble Packing in 3D

PubMed Central

Tanaka, Daigo; Shimada, Kenji; Rossi, Michael R.; Rabin, Yoed

2008-01-01

As part of an ongoing project to develop automated tools for cryosurgery planning, the current study focuses on the development of a 3D bubble packing method. A proof-of-concept for the new method is demonstrated on five prostate models, reconstructed from ultrasound images. The new method is a modification of an established method in 2D. Ellipsoidal bubbles are packed in the volume of the prostate in the current study; such bubbles can be viewed as a first-order approximation of a frozen region around a single cryoprobe. When all cryoprobes are inserted to the same depth, optimum planning was found to occur at about 60% of the length of the prostate (measured from its apex), which leads to cooling of approximately 75% of the prostate volume below a specific temperature threshold of −22°C. Bubble packing has the potential to dramatically reduce the run time for automated planning. PMID:17963095

Cryosurgery planning using bubble packing in 3D.

PubMed

Tanaka, Daigo; Shimada, Kenji; Rossi, Michael R; Rabin, Yoed

2008-04-01

As part of an ongoing project to develop automated tools for cryosurgery planning, the current study focuses on the development of a 3D bubble packing method. A proof-of-concept for the new method is demonstrated on five prostate models, reconstructed from ultrasound images. The new method is a modification of an established method in 2D. Ellipsoidal bubbles are packed in the volume of the prostate in the current study; such bubbles can be viewed as a first-order approximation of a frozen region around a single cryoprobe. When all cryoprobes are inserted to the same depth, optimum planning was found to occur at about 60% of the length of the prostate (measured from its apex), which leads to cooling of approximately 75% of the prostate volume below a specific temperature threshold of - 22 degrees C. Bubble packing has the potential to dramatically reduce the run time for automated planning.

Captive breeding and reintroduction of the endangered masked bobwhite

USGS Publications Warehouse

Carpenter, J.W.; Gabel, R.R.; Goodwin, J.G.

1991-01-01

Efforts to restore the endangered masked bobwhite (Colinus virginianus ridgwayi) to its former range have required 1) habitat acquisition, restoration, and preservation; 2) captive propagation; and 3) reintroduction .bf captive-bred stock. In its role to recover the masked bobwhite, the Patuxent Wildlife Research Center (U.S. Fish and Wildli e Service) has refined captive breeding techniques; provided captive-produced stock for release; conducted field research on the distribution, limiting factors, and habitat characteristics of this species; and developed release methods. Techniques for the husbandry and captive management, breeding, artificial incubation and hatching of eggs, and rearing of young of the masked bobwhite have been developed. Successful reintroduction techniques for the masked bobwhite have included prerelease conditioning and/or cross-fostering of captive-reared masked bobwhite chicks to a wild-caught, related, vasectomized bobwhite species and their release to the wild as family units. In addition, the establishment by the U. S. Fish and Wildlife Service of the Buenos Aires National Wildlife Refuge in 1985 has further enhanced the potential for establishing a self-sustaining population of the masked bobwhite in the U. S. Through continued releases and active management of habitat, therefore, it is believed that the masked bobwhite can become permanently established at the refuge to ensure its continued survival in the wild.

A new method of quantitative cavitation assessment in the field of a lithotripter.

PubMed

Jöchle, K; Debus, J; Lorenz, W J; Huber, P

1996-01-01

Transient cavitation seems to be a very important effect regarding the interaction of pulsed high-energy ultrasound with biologic tissues. Using a newly developed laser optical system we are able to determine the life-span of transient cavities (relative error less than +/- 5%) in the focal region of a lithotripter (Lithostar, Siemens). The laser scattering method is based on the detection of scattered laser light reflected during a bubble's life. This method requires no sort of sensor material in the pathway of the sound field. Thus, the method avoids any interference with bubble dynamics during the measurement. The knowledge of the time of bubble decay allows conclusions to be reached on the destructive power of the cavities. By combining the results of life-span measurements with the maximum bubble radius using stroboscopic photographs we found that the measured time of bubble decay and the predicted time using Rayleigh's law only differs by about 13% even in the case of complex bubble fields. It can be shown that the laser scattering method is feasible to assess cavitation events quantitatively. Moreover, it will enable us to compare different medical ultrasound sources that have the capability to generate cavitation.

Generation of Submicron Bubbles using Venturi Tube Method

NASA Astrophysics Data System (ADS)

Wiraputra, I. G. P. A. E.; Edikresnha, D.; Munir, M. M.; Khairurrijal

2016-08-01

In this experiment, submicron bubbles that have diameters less than 1 millimeter were generated by mixing water and gas by hydrodynamic cavitation method. The water was forced to pass through a venturi tube in which the speed of the water will increase in the narrow section, the throat, of the venturi. When the speed of water increased, the pressure would drop at the throat of the venturi causing the outside air to be absorbed via the gas inlet. The gas was then trapped inside the water producing bubbles. The effects of several physical parameters on the characteristics of the bubbles will be discussed thoroughly in this paper. It was found that larger amount of gas pressure during compression will increase the production rate of bubbles and increase the density of bubble within water.

Simulating the universe(s) III: observables for the full bubble collision spacetime

NASA Astrophysics Data System (ADS)

Johnson, Matthew C.; Wainwright, Carroll L.; Aguirre, Anthony; Peiris, Hiranya V.

2016-07-01

This is the third paper in a series establishing a quantitative relation between inflationary scalar field potential landscapes and the relic perturbations left by the collision between bubbles produced during eternal inflation. We introduce a new method for computing cosmological observables from numerical relativity simulations of bubble collisions in one space and one time dimension. This method tiles comoving hypersurfaces with locally-perturbed Friedmann-Robertson-Walker coordinate patches. The method extends previous work, which was limited to the spacetime region just inside the future light cone of the collision, and allows us to explore the full bubble-collision spacetime. We validate our new methods against previous work, and present a full set of predictions for the comoving curvature perturbation and local negative spatial curvature produced by identical and non-identical bubble collisions, in single scalar field models of eternal inflation. In both collision types, there is a non-zero contribution to the spatial curvature and cosmic microwave background quadrupole. Some collisions between non-identical bubbles excite wall modes, giving extra structure to the predicted temperature anisotropies. We comment on the implications of our results for future observational searches. For non-identical bubble collisions, we also find that the surfaces of constant field can readjust in the presence of a collision to produce spatially infinite sections that become nearly homogeneous deep into the region affected by the collision. Contrary to previous assumptions, this is true even in the bubble into which the domain wall is accelerating.

Numerical simulation of bubble plumes and an analysis of their seismic attributes

NASA Astrophysics Data System (ADS)

Li, Canping; Gou, Limin; You, Jiachun

2017-04-01

To study the bubble plume's seismic response characteristics, the model of a plume water body has been built in this article using the bubble-contained medium acoustic velocity model and the stochastic medium theory based on an analysis of both the acoustic characteristics of a bubble-contained water body and the actual features of a plume. The finite difference method is used for forward modelling, and the single-shot seismic record exhibits the characteristics of a scattered wave field generated by a plume. A meaningful conclusion is obtained by extracting seismic attributes from the pre-stack shot gather record of a plume. The values of the amplitude-related seismic attributes increase greatly as the bubble content goes up, and changes in bubble radius will not cause seismic attributes to change, which is primarily observed because the bubble content has a strong impact on the plume's acoustic velocity, while the bubble radius has a weak impact on the acoustic velocity. The above conclusion provides a theoretical reference for identifying hydrate plumes using seismic methods and contributes to further study on hydrate decomposition and migration, as well as on distribution of the methane bubble in seawater.

Applicability of contact angle techniques used in the analysis of contact lenses, part 1: comparative methodologies.

PubMed

Campbell, Darren; Carnell, Sarah Maria; Eden, Russell John

2013-05-01

Contact angle, as a representative measure of surface wettability, is often employed to interpret contact lens surface properties. The literature is often contradictory and can lead to confusion. This literature review is part of a series regarding the analysis of hydrogel contact lenses using contact angle techniques. Here we present an overview of contact angle terminology, methodology, and analysis. Having discussed this background material, subsequent parts of the series will discuss the analysis of contact lens contact angles and evaluate differences in published laboratory results. The concepts of contact angle, wettability and wetting are presented as an introduction. Contact angle hysteresis is outlined and highlights the advantages in using dynamic analytical techniques over static methods. The surface free energy of a material illustrates how contact angle analysis is capable of providing supplementary surface characterization. Although single values are able to distinguish individual material differences, surface free energy and dynamic methods provide an improved understanding of material behavior. The frequently used sessile drop, captive bubble, and Wilhelmy plate techniques are discussed. Their use as both dynamic and static methods, along with the advantages and disadvantages of each technique, is explained. No single contact angle technique fully characterizes the wettability of a material surface, and the application of complimenting methods allows increased characterization. At present, there is not an ISO standard method designed for soft materials. It is important that each contact angle technique has a standard protocol, as small protocol differences between laboratories often contribute to a variety of published data that are not easily comparable.

Improved Reading Gate For Vertical-Bloch-Line Memory

NASA Technical Reports Server (NTRS)

Wu, Jiin-Chuan; Stadler, Henry L.; Katti, Romney R.

1994-01-01

Improved design for reading gate of vertical-Bloch-line magnetic-bubble memory increases reliability of discrimination between binary ones and zeros. Magnetic bubbles that signify binary "1" and "0" produced by applying sufficiently large chopping currents to memory stripes. Bubbles then propagated differentially in bubble sorter. Method of discriminating between ones and zeros more reliable.

Microbiological evaluation of different strategies for management of snakes in captivity.

PubMed

Campagner, M V; Bosco, S M G; Bagagli, E; Cunha, M L R S; Jeronimo, B C; Saad, E; Biscola, N P; Ferreira, R S; Barraviera, B

2012-01-01

Keeping snakes in captivity to produce venom for scientific research and production of inputs is now a worldwide practice. Maintaining snakes in captivity involves capture, infrastructure investments, management techniques, and appropriate qualified personnel. Further, the success of the project requires knowledge of habitat, nutrition, and reproduction, and control of opportunistic infections. This study evaluated the management of snakes in three types of captivity (quarantine, intensive, and semiextensive) and diagnosed bacterial and fungal contaminants. A bacteriological profile was obtained by swabbing the oral and cloacal cavities, scales, and venoms of healthy adult snakes from Bothrops jararaca (Bj) and Crotalus durissus terrificus (Cdt). There was predominance of Enterobacteriaceae, especially non-fermenting Gram-negative bacilli excluding Pseudomonas spp and Gram- positive bacteria. Statistically, intensive captivity resulted in the highest number of bacterial isolates, followed by recent capture (quarantine) and by semiextensive captivity. No statistical difference was found between Bj and Cdt bacterial frequency. In vitro bacterial susceptibility testing found the highest resistance against the semisynthetic penicillins (amoxicillin and ampicillin) and highest sensitivity to amicacin and tobramycin aminoglycosides. To evaluate mycological profile of snakes from intensive captivity, samples were obtained from two healthy Bj and one B. moojeni, one B. pauloensis, and one Cdt showing whitish lesions on the scales suggestive of ringworm. Using conventional methods and DNA-based molecular procedures, five samples of Trichosporon asahii were identified. Despite the traditional role of intense captivity in ophidian venom production, semiextensive captivity was more effective in the present study by virtue of presenting superior control of bacterial and fungal transmission, easier management, lowest cost, and decreased rate of mortality; therefore, it should be considered as a good alternative for tropical countries.

Taylor bubbles at high viscosity ratios: experiments and numerical simulations

NASA Astrophysics Data System (ADS)

Hewakandamby, Buddhika; Hasan, Abbas; Azzopardi, Barry; Xie, Zhihua; Pain, Chris; Matar, Omar

2015-11-01

The Taylor bubble is a single long bubble which nearly fills the entire cross section of a liquid-filled circular tube, often occurring in gas-liquid slug flows in many industrial applications, particularly oil and gas production. The objective of this study is to investigate the fluid dynamics of three-dimensional Taylor bubble rising in highly viscous silicone oil in a vertical pipe. An adaptive unstructured mesh modelling framework is adopted here which can modify and adapt anisotropic unstructured meshes to better represent the underlying physics of bubble rising and reduce computational effort without sacrificing accuracy. The numerical framework consists of a mixed control volume and finite element formulation, a `volume of fluid'-type method for the interface-capturing based on a compressive control volume advection method, and a force-balanced algorithm for the surface tension implementation. Experimental results for the Taylor bubble shape and rise velocity are presented, together with numerical results for the dynamics of the bubbles. A comparison of the simulation predictions with experimental data available in the literature is also presented to demonstrate the capabilities of our numerical method. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

Fabrication of Acrylonitrile-Butadiene-Styrene Nanostructures with Anodic Alumina Oxide Templates, Characterization and Biofilm Development Test for Staphylococcus epidermidis

PubMed Central

Desrousseaux, Camille; Cueff, Régis; Aumeran, Claire; Garrait, Ghislain; Mailhot-Jensen, Bénédicte; Traoré, Ousmane; Sautou, Valérie

2015-01-01

Medical devices can be contaminated by microbial biofilm which causes nosocomial infections. One of the strategies for the prevention of such microbial adhesion is to modify the biomaterials by creating micro or nanofeatures on their surface. This study aimed (1) to nanostructure acrylonitrile-butadiene-styrene (ABS), a polymer composing connectors in perfusion devices, using Anodic Alumina Oxide templates, and to control the reproducibility of this process; (2) to characterize the physico-chemical properties of the nanostructured surfaces such as wettability using captive-bubble contact angle measurement technique; (3) to test the impact of nanostructures on Staphylococcus epidermidis biofilm development. Fabrication of Anodic Alumina Oxide molds was realized by double anodization in oxalic acid. This process was reproducible. The obtained molds present hexagonally arranged 50 nm diameter pores, with a 100 nm interpore distance and a length of 100 nm. Acrylonitrile-butadiene-styrene nanostructures were successfully prepared using a polymer solution and two melt wetting methods. For all methods, the nanopicots were obtained but inside each sample their length was different. One method was selected essentially for industrial purposes and for better reproducibility results. The flat ABS surface presents a slightly hydrophilic character, which remains roughly unchanged after nanostructuration, the increasing apparent wettability observed in that case being explained by roughness effects. Also, the nanostructuration of the polymer surface does not induce any significant effect on Staphylococcus epidermidis adhesion. PMID:26284922

Improvement of ore recovery efficiency in a flotation column cell using ultra-sonic enhanced bubbles

NASA Astrophysics Data System (ADS)

Filippov, L. O.; Royer, J. J.; Filippova, I. V.

2017-07-01

The ore process flotation technique is enhanced by using external ultra-sonic waves. Compared to the classical flotation method, the application of ultrasounds to flotation fluids generates micro-bubbles by hydrodynamic cavitation. Flotation performances increase was modelled as a result of increased probabilities of the particle-bubble attachment and reduced detachment probability under sonication. A simplified analytical Navier-Stokes model is used to predict the effect of ultrasonic waves on bubble behavior. If the theory is verified by experimentation, it predicts that the ultrasonic waves would create cavitation micro-bubbles, smaller than the flotation bubble added by the gas sparger. This effect leads to increasing the number of small bubbles in the liquid which promote particle-bubble attachment through coalescence between bubbles and micro-bubbles. The decrease in the radius of the flotation bubbles under external vibration forces has an additional effect by enhancing the bubble-particle collision. Preliminary results performed on a potash ore seem to confirm the theory.

Expansion of a compressible gas bubble in Stokes flow

NASA Astrophysics Data System (ADS)

Pozrikidis, C.

2001-09-01

The flow-induced deformation of an inviscid bubble occupied by a compressible gas and suspended in an ambient viscous liquid is considered at low Reynolds numbers with particular reference to the pressure developing inside the bubble. Ambient fluid motion alters the bubble pressure with respect to that established in the quiescent state, and requires the bubble to expand or contract according to an assumed equation of state. When changes in the bubble volume are prohibited by a global constraint on the total volume of the flow, the ambient pressure is modified while the bubble pressure remains constant during the deformation. A numerical method is developed for evaluating the pressure inside a two-dimensional bubble in an ambient Stokes flow on the basis of the normal component of the interfacial force balance involving the capillary pressure, the normal viscous stress, and the pressure at the free surface on the side of the liquid; the last is computed by evaluating a strongly singular integral. Dynamical simulations of bubble deformation are performed using the boundary integral method properly implemented to remove the multiplicity of solutions due to the a priori unknown rate of expansion, and three particular problems are discussed in detail: the shrinkage of a bubble at a specified rate, the deformation of a bubble subject to simple shear flow, and the deformation of a bubble subject to a purely elongational flow. In the case of shrinkage, it is found that the surface tension plays a critical role in determining the behaviour of the bubble pressure near the critical time when the bubble disappears. In the case of shear or elongational flow, it is found that the bubble contracts during an initial period of deformation from the circular shape, and then it expands to obtain a stationary shape whose area is higher than that assumed in the quiescent state. Expansion may destabilize the bubble by raising the capillary number above the critical threshold under which stationary shapes can be found.

A fractional Fourier transform analysis of a bubble excited by an ultrasonic chirp.

PubMed

Barlow, Euan; Mulholland, Anthony J

2011-11-01

The fractional Fourier transform is proposed here as a model based, signal processing technique for determining the size of a bubble in a fluid. The bubble is insonified with an ultrasonic chirp and the radiated pressure field is recorded. This experimental bubble response is then compared with a series of theoretical model responses to identify the most accurate match between experiment and theory which allows the correct bubble size to be identified. The fractional Fourier transform is used to produce a more detailed description of each response, and two-dimensional cross correlation is then employed to identify the similarities between the experimental response and each theoretical response. In this paper the experimental bubble response is simulated by adding various levels of noise to the theoretical model output. The method is compared to the standard technique of using time-domain cross correlation. The proposed method is shown to be far more robust at correctly sizing the bubble and can cope with much lower signal to noise ratios.

Electrical capacitance volume tomography (ECVT) applied to bubbling fluid beds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weber, J., Mei, J.

2012-01-01

These presentation visuals illustrate the apparatus and method for applying Electrical Capacitance Volume Tomography (ECVT) to bubbling fluid beds to their solid fraction and bubble properties. Results are compared to estimated values.

Selective detection of cavitation bubbles by triplet pulse sequence in high-intensity focused ultrasound treatment

NASA Astrophysics Data System (ADS)

Iwasaki, Ryosuke; Nagaoka, Ryo; Yoshizawa, Shin; Umemura, Shin-ichiro

2018-07-01

Acoustic cavitation bubbles are known to enhance the heating effect in high-intensity focused ultrasound (HIFU) treatment. The detection of cavitation bubbles with high sensitivity and selectivity is required to predict the therapeutic and side effects of cavitation, and ensure the efficacy and safety of the treatment. A pulse inversion (PI) technique has been widely used for imaging microbubbles through enhancing the second-harmonic component of echo signals. However, it has difficulty in separating the nonlinear response of microbubbles from that due to nonlinear propagation. In this study, a triplet pulse (3P) method was investigated to specifically image cavitation bubbles by extracting the 1.5th fractional harmonic component. The proposed 3P method depicted cavitation bubbles with a contrast ratio significantly higher than those in conventional imaging methods with and without PI. The results suggest that the 3P method is effective for specifically detecting microbubbles in cavitation-enhanced HIFU treatment.

Benefits of polidocanol endovenous microfoam (Varithena®) compared with physician-compounded foams

PubMed Central

Carugo, Dario; Ankrett, Dyan N; Zhao, Xuefeng; Zhang, Xunli; Hill, Martyn; O’Byrne, Vincent; Hoad, James; Arif, Mehreen; Wright, David DI

2015-01-01

Objective To compare foam bubble size and bubble size distribution, stability, and degradation rate of commercially available polidocanol endovenous microfoam (Varithena®) and physician-compounded foams using a number of laboratory tests. Methods Foam properties of polidocanol endovenous microfoam and physician-compounded foams were measured and compared using a glass-plate method and a Sympatec QICPIC image analysis method to measure bubble size and bubble size distribution, Turbiscan™ LAB for foam half time and drainage and a novel biomimetic vein model to measure foam stability. Physician-compounded foams composed of polidocanol and room air, CO2, or mixtures of oxygen and carbon dioxide (O2:CO2) were generated by different methods. Results Polidocanol endovenous microfoam was found to have a narrow bubble size distribution with no large (>500 µm) bubbles. Physician-compounded foams made with the Tessari method had broader bubble size distribution and large bubbles, which have an impact on foam stability. Polidocanol endovenous microfoam had a lower degradation rate than any physician-compounded foams, including foams made using room air (p < 0.035). The same result was obtained at different liquid to gas ratios (1:4 and 1:7) for physician-compounded foams. In all tests performed, CO2 foams were the least stable and different O2:CO2 mixtures had intermediate performance. In the biomimetic vein model, polidocanol endovenous microfoam had the slowest degradation rate and longest calculated dwell time, which represents the length of time the foam is in contact with the vein, almost twice that of physician-compounded foams using room air and eight times better than physician-compounded foams prepared using equivalent gas mixes. Conclusion Bubble size, bubble size distribution and stability of various sclerosing foam formulations show that polidocanol endovenous microfoam results in better overall performance compared with physician-compounded foams. Polidocanol endovenous microfoam offers better stability and cohesive properties in a biomimetic vein model compared to physician-compounded foams. Polidocanol endovenous microfoam, which is indicated in the United States for treatment of great saphenous vein system incompetence, provides clinicians with a consistent product with enhanced handling properties. PMID:26036246

Scalable and reusable micro-bubble removal method to flatten large-area 2D materials

NASA Astrophysics Data System (ADS)

Pham, Phi H. Q.; Quach, Nhi V.; Li, Jinfeng; Burke, Peter J.

2018-04-01

Bubbles generated during electro-delamination and chemical etch during large-area two-dimensional (2D) material transfer has been shown to cause rippling, and consequently, results in tears and wrinkles in the transferred film. Here, we demonstrate a scalable and reusable method to remove surface adhered micro-bubbles by using hydrophobic surfaces modified by self-assembled monolayers (SAMs). Bubble removal allows the 2D film to flatten out and prevents the formation of defects. Electrical characterization was used to verify improved transfer quality and was confirmed by increased field-effect mobility and decreased sheet resistance. Raman spectroscopy was also used to validate enhanced electrical quality following transfer. The bubble removal method can be applied to an assortment of 2D materials using diverse hydrophobic SAM variants. Our studies can be integrated into large scale applications and will lead to improved large-area 2D electronics in general.

Experimental and numerical study of the effects of a wall on the coalescence and collapse of bubble pairs

NASA Astrophysics Data System (ADS)

Han, Rui; Zhang, A.-Man; Li, Shuai; Zong, Zhi

2018-04-01

Two-bubble interaction is the most fundamental problem in multi-bubbles dynamics, which is crucial in many practical applications involving air-gun arrays and underwater explosions. In this paper, we experimentally and numerically investigate coalescence, collapse, and rebound of non-buoyant bubble pairs below a rigid wall. Two oscillating vapor bubbles with similar size are generated simultaneously near a rigid wall in axisymmetric configuration using the underwater electric discharge method, and the physical process is captured by a high-speed camera. Numerical simulations are conducted based on potential flow theory coupled with the boundary integral method. Our numerical results show excellent agreement with the experimental data until the splashing of the jet impact sets in. With different ranges of γbw (the dimensionless distance between the rigid wall and the nearest bubble center), the interaction between the coalesced bubble and the rigid wall is divided into three types, i.e., "weak," "intermediate," and "strong." As γbw decreases, the contact point of the two axial jets migrates toward the wall. In "strong interaction" cases, only an upward jet towards the upper rigid wall forms and a secondary jet with a larger width appears at the base of the first jet. The collapsing coalesced bubble in a toroidal form splits into many smaller bubbles due to the instabilities and presents as bubble clouds during the rebounding phase, which may lead to a weakened pressure wave because the focusing energy associated with the collapsing bubble is disintegrated.

A numerical framework for bubble transport in a subcooled fluid flow

NASA Astrophysics Data System (ADS)

Jareteg, Klas; Sasic, Srdjan; Vinai, Paolo; Demazière, Christophe

2017-09-01

In this paper we present a framework for the simulation of dispersed bubbly two-phase flows, with the specific aim of describing vapor-liquid systems with condensation. We formulate and implement a framework that consists of a population balance equation (PBE) for the bubble size distribution and an Eulerian-Eulerian two-fluid solver. The PBE is discretized using the Direct Quadrature Method of Moments (DQMOM) in which we include the condensation of the bubbles as an internal phase space convection. We investigate the robustness of the DQMOM formulation and the numerical issues arising from the rapid shrinkage of the vapor bubbles. In contrast to a PBE method based on the multiple-size-group (MUSIG) method, the DQMOM formulation allows us to compute a distribution with dynamic bubble sizes. Such a property is advantageous to capture the wide range of bubble sizes associated with the condensation process. Furthermore, we compare the computational performance of the DQMOM-based framework with the MUSIG method. The results demonstrate that DQMOM is able to retrieve the bubble size distribution with a good numerical precision in only a small fraction of the computational time required by MUSIG. For the two-fluid solver, we examine the implementation of the mass, momentum and enthalpy conservation equations in relation to the coupling to the PBE. In particular, we propose a formulation of the pressure and liquid continuity equations, that was shown to correctly preserve mass when computing the vapor fraction with DQMOM. In addition, the conservation of enthalpy was also proven. Therefore a consistent overall framework that couples the PBE and two-fluid solvers is achieved.

Improvement in the amine glass platform by bubbling method for a DNA microarray

PubMed Central

Jee, Seung Hyun; Kim, Jong Won; Lee, Ji Hyeong; Yoon, Young Soo

2015-01-01

A glass platform with high sensitivity for sexually transmitted diseases microarray is described here. An amino-silane-based self-assembled monolayer was coated on the surface of a glass platform using a novel bubbling method. The optimized surface of the glass platform had highly uniform surface modifications using this method, as well as improved hybridization properties with capture probes in the DNA microarray. On the basis of these results, the improved glass platform serves as a highly reliable and optimal material for the DNA microarray. Moreover, in this study, we demonstrated that our glass platform, manufactured by utilizing the bubbling method, had higher uniformity, shorter processing time, lower background signal, and higher spot signal than the platforms manufactured by the general dipping method. The DNA microarray manufactured with a glass platform prepared using bubbling method can be used as a clinical diagnostic tool. PMID:26468293

Improvement in the amine glass platform by bubbling method for a DNA microarray.

PubMed

Jee, Seung Hyun; Kim, Jong Won; Lee, Ji Hyeong; Yoon, Young Soo

2015-01-01

A glass platform with high sensitivity for sexually transmitted diseases microarray is described here. An amino-silane-based self-assembled monolayer was coated on the surface of a glass platform using a novel bubbling method. The optimized surface of the glass platform had highly uniform surface modifications using this method, as well as improved hybridization properties with capture probes in the DNA microarray. On the basis of these results, the improved glass platform serves as a highly reliable and optimal material for the DNA microarray. Moreover, in this study, we demonstrated that our glass platform, manufactured by utilizing the bubbling method, had higher uniformity, shorter processing time, lower background signal, and higher spot signal than the platforms manufactured by the general dipping method. The DNA microarray manufactured with a glass platform prepared using bubbling method can be used as a clinical diagnostic tool.

The bubble method of water purification

NASA Astrophysics Data System (ADS)

Smirnov, B. M.; Babaeva, N. Yu.; Naidis, G. V.; Panov, V. A.; Saveliev, A. S.; Son, E. E.; Tereshonok, D. V.

2018-02-01

The processes of water purification from admixture molecules are analyzed. The purification rate is limited due to a low diffusion coefficient of the admixture molecules in water. At non-small concentrations of the admixture molecules, the water purication can proceed through association of molecules in condensed nanoparticles which fall on the bottom of the water volume. The rate of association may be increased in an external electric field, but in reality this cannot change significantly the rate of the purification process. The bubble method of water purification is considered, where air bubbles formed at the bottom of the water volume, transfer admixture molecules to the interface. This method allows one to clean small water volumes fast. This mechanism of water purification is realized experimentally and exhibits the promises of the bubble purification method.

Monte Carlo simulation of spectral reflectance and BRDF of the bubble layer in the upper ocean.

PubMed

Ma, Lanxin; Wang, Fuqiang; Wang, Chengan; Wang, Chengchao; Tan, Jianyu

2015-09-21

The presence of bubbles can significantly change the radiative properties of seawater and these changes will affect remote sensing and underwater target detection. In this work, the spectral reflectance and bidirectional reflectance characteristics of the bubble layer in the upper ocean are investigated using the Monte Carlo method. The Hall-Novarini (HN) bubble population model, which considers the effect of wind speed and depth on the bubble size distribution, is used. The scattering coefficients and the scattering phase functions of bubbles in seawater are calculated using Mie theory, and the inherent optical properties of seawater for wavelengths between 300 nm and 800 nm are related to chlorophyll concentration (Chl). The effects of bubble coating, Chl, and bubble number density on the spectral reflectance of the bubble layer are studied. The bidirectional reflectance distribution function (BRDF) of the bubble layer for both normal and oblique incidence is also investigated. The results show that bubble populations in clear waters under high wind speed conditions significantly influence the reflection characteristics of the bubble layer. Furthermore, the contribution of bubble populations to the reflection characteristics is mainly due to the strong backscattering of bubbles that are coated with an organic film.

Study on Pressure Wave Propagation in a Liquid Containing Spherical Bubbles in a Rectangular Duct

NASA Astrophysics Data System (ADS)

Kawahara, Junya; Watanabe, Masao; Kobayashi, Kazumichi

2015-12-01

Pressure wave propagation in a liquid containing several bubbles is numerically investigated. We simulate liner plane wave propagation in a liquid containing 10 spherical bubbles in a rectangular duct with the equation of motion for N spherical bubbles. The sound pressures of the reflected waves from the rigid walls are calculated by using the method of images. The result shows that the phase velocity of the pressure wave propagating in the liquid containing 10 spherical bubbles in the duct agrees well with the low-frequency speed of sound in a homogeneous bubbly liquid.

Numerical studies of cavitation erosion on an elastic-plastic material caused by shock-induced bubble collapse

NASA Astrophysics Data System (ADS)

Turangan, C. K.; Ball, G. J.; Jamaluddin, A. R.; Leighton, T. G.

2017-09-01

We present a study of shock-induced collapse of single bubbles near/attached to an elastic-plastic solid using the free-Lagrange method, which forms the latest part of our shock-induced collapse studies. We simulated the collapse of 40 μm radius single bubbles near/attached to rigid and aluminium walls by a 60 MPa lithotripter shock for various scenarios based on bubble-wall separations, and the collapse of a 255 μm radius bubble attached to aluminium foil with a 65 MPa lithotripter shock. The coupling of the multi-phases, compressibility, axisymmetric geometry and elastic-plastic material model within a single solver has enabled us to examine the impingement of high-speed liquid jets from the shock-induced collapsing bubbles, which imposes an extreme compression in the aluminium that leads to pitting and plastic deformation. For certain scenarios, instead of the high-speed jet, a radially inwards flow along the aluminium surface contracts the bubble to produce a `mushroom shape'. This work provides methods for quantifying which parameters (e.g. bubble sizes and separations from the solid) might promote or inhibit erosion on solid surfaces.

Feasibility of an in situ measurement device for bubble size and distribution.

PubMed

Junker, Beth; Maciejak, Walter; Darnell, Branson; Lester, Michael; Pollack, Michael

2007-09-01

The feasibility of in situ measurement device for bubble size and distribution was explored. A novel in situ probe measurement system, the EnviroCam, was developed. Where possible, this probe incorporated strengths, and minimized weaknesses of historical and currently available real-time measurement methods for bubbles. The system was based on a digital, high-speed, high resolution, modular camera system, attached to a stainless steel shroud, compatible with standard Ingold ports on fermenters. Still frames and/or video were produced, capturing bubbles passing through the notch of the shroud. An LED light source was integral with the shroud. Bubbles were analyzed using customized commercially available image analysis software and standard statistical methods. Using this system, bubble sizes were measured as a function of various operating parameters (e.g., agitation rate, aeration rate) and as a function of media properties (e.g., viscosity, antifoam, cottonseed flour, and microbial/animal cell broths) to demonstrate system performance and its limitations. For selected conditions, mean bubble size changes qualitatively compared favorably with published relationships. Current instrument measurement capabilities were limited primarily to clear solutions that did not contain large numbers of overlapping bubbles.

Bubbles in extended inflation and multi-production of universes

NASA Astrophysics Data System (ADS)

Sakai, Nobuyuki; Maeda, Kei-ichi

Developing the thin-wall method of Israel, we present a formalism to investigate bubble dynamics in generalized Einstein theories. We derive the equations of motion for a bubble, finding that the space-time inside a bubble is always inhomogeneous. Applying this formalism to extended inflation, we find the following two results: (1) Any true vacuum bubble expands, contrary to the results of Goldwirth-Zaglauer, who claim that bubbles created initially later collapse. We show that their initial conditions for collapsing bubbles are physically inconsistent. (2) Concerning the global space-time structure of the Universe in extended inflation, we show that worm-holes are produced as in old inflation, resulting in the multi-production of universes.

Characterization of fission gas bubbles in irradiated U-10Mo fuel

DOE PAGES

Casella, Andrew M.; Burkes, Douglas E.; MacFarlan, Paul J.; ...

2017-06-06

A simple, repeatable method for characterization of fission gas bubbles in irradiated U-Mo fuels has been developed. This method involves mechanical potting and polishing of samples along with examination with a scanning electron microscope located outside of a hot cell. The commercially available software packages CellProfiler, MATLAB, and Mathematica are used to segment and analyze the captured images. The results are compared and contrasted. Finally, baseline methods for fission gas bubble characterization are suggested for consideration and further development.

Diagnosis-based treatment of helminths in captive and wild cheetahs (Acinonyx jubatus).

PubMed

Mény, Marie; Schmidt-Küntzel, Anne; Marker, Laurie L

2012-12-01

This study was designed to identify endoparasites in captive cheetahs (Acinonyx jubatus) living in a seminatural captive environment in north-central Namibia. Results were used to assess the need for anthelmintic treatment and for the selection of an appropriate drug. The study assessed fecal parasite excretion qualitatively and quantitatively using a fecal flotation method during the winter of 2009. Four different species of parasites (two nematodes and two coccidias) were identified. Parasite excretion rates were found to be significantly lower than that of wild cheetahs living in the same area. Samples of the wild cheetahs were obtained at the time of anesthesia or were attributed to the wild individuals using genetic profiling. Captive cheetahs were dewormed with fenbendazole, whereas wild cheetahs were treated using ivermectin. Efficacy of these treatments was demonstrated at the end of the study.

Possible high sonic velocity due to the inclusion of gas bubbles in water

NASA Astrophysics Data System (ADS)

Banno, T.; Mikada, H.; Goto, T.; Takekawa, J.

2010-12-01

If formation water becomes multi-phase by inclusion of gas bubbles, sonic velocities would be strongly influenced. In general, sonic velocities are knocked down due to low bulk moduli of the gas bubbles. However, sonic velocities may increase depending on the size of gas bubbles, when the bubbles in water or other media oscillate due to incoming sonic waves. Sonic waves are scattered by the bubbles and the superposition of the incoming and the scattered waves result in resonant-frequency-dependent behavior. The phase velocity of sonic waves propagating in fluids containing bubbles, therefore, probably depends on their frequencies. This is a typical phenomenon called “wave dispersion.” So far we have studied about the bubble impact on sonic velocity in bubbly media, such as the formation that contains gas bubbles. As a result, it is shown that the bubble resonance effect is a key to analyze the sonic phase velocity increase. Therefore to evaluate the resonance frequency of bubbles is important to solve the frequency response of sonic velocity in formations having bubbly fluids. There are several analytical solutions of the resonance frequency of bubbles in water. Takahira et al. (1994) derived a equation that gives us the resonance frequency considering bubble - bubble interactions. We have used this theory to calculate resonance frequency of bubbles at the previous work. However, the analytical solution of the Takahira’s equation is based on several assumptions. Therefore we used a numerical approach to calculate the bubble resonance effect more precisely in the present study. We used the boundary element method (BEM) to reproduce a bubble oscillation in incompressible liquid. There are several reasons to apply the BEM. Firstly, it arrows us to model arbitrarily sets and shapes of bubbles. Secondly, it is easy to use the BEM to reproduce a boundary-surface between liquid and gas. The velocity potential of liquid surrounding a bubble satisfies the Laplace equation when the liquid is supposed to be incompressible. We got the boundary integral equation from the Laplace equation and solved the boundary integral equation by the BEM. Then, we got the gradient of the velocity potential from the BEM. We used this gradient to get time derivative of the velocity potential from the Bernouii’s equation. And we used the second order Adams-Bashforth method to execute time integration of the velocity potential. We conducted this scheme iteratively to calculate a bubble oscillation. At each time step, we input a pressure change as a sinusoidal wave. As a result, we observed a bubble oscillation following the pressure frequency. We also evaluated the resonance frequency of a bubble by changing the pressure frequency. It showed a good agreement with the analytical solution described above. Our future work is to extend the calculation into plural bubbles condition. We expect that interaction between bubbles becomes strong and resonance frequency of bubbles becomes small when distance between bubbles becomes small.

Bubble memory module for spacecraft application

NASA Technical Reports Server (NTRS)

Hayes, P. J.; Looney, K. T.; Nichols, C. D.

1985-01-01

Bubble domain technology offers an all-solid-state alternative for data storage in onboard data systems. A versatile modular bubble memory concept was developed. The key module is the bubble memory module which contains all of the storage devices and circuitry for accessing these devices. This report documents the bubble memory module design and preliminary hardware designs aimed at memory module functional demonstration with available commercial bubble devices. The system architecture provides simultaneous operation of bubble devices to attain high data rates. Banks of bubble devices are accessed by a given bubble controller to minimize controller parts. A power strobing technique is discussed which could minimize the average system power dissipation. A fast initialization method using EEPROM (electrically erasable, programmable read-only memory) devices promotes fast access. Noise and crosstalk problems and implementations to minimize these are discussed. Flight memory systems which incorporate the concepts and techniques of this work could now be developed for applications.

Bubble behavior characteristics based on virtual binocular stereo vision

NASA Astrophysics Data System (ADS)

Xue, Ting; Xu, Ling-shuang; Zhang, Shang-zhen

2018-01-01

The three-dimensional (3D) behavior characteristics of bubble rising in gas-liquid two-phase flow are of great importance to study bubbly flow mechanism and guide engineering practice. Based on the dual-perspective imaging of virtual binocular stereo vision, the 3D behavior characteristics of bubbles in gas-liquid two-phase flow are studied in detail, which effectively increases the projection information of bubbles to acquire more accurate behavior features. In this paper, the variations of bubble equivalent diameter, volume, velocity and trajectory in the rising process are estimated, and the factors affecting bubble behavior characteristics are analyzed. It is shown that the method is real-time and valid, the equivalent diameter of the rising bubble in the stagnant water is periodically changed, and the crests and troughs in the equivalent diameter curve appear alternately. The bubble behavior characteristics as well as the spiral amplitude are affected by the orifice diameter and the gas volume flow.

Bubble dynamics in a compressible liquid in contact with a rigid boundary

PubMed Central

Wang, Qianxi; Liu, Wenke; Zhang, A. M.; Sui, Yi

2015-01-01

A bubble initiated near a rigid boundary may be almost in contact with the boundary because of its expansion and migration to the boundary, where a thin layer of water forms between the bubble and the boundary thereafter. This phenomenon is modelled using the weakly compressible theory coupled with the boundary integral method. The wall effects are modelled using the imaging method. The numerical instabilities caused by the near contact of the bubble surface with the boundary are handled by removing a thin layer of water between them and joining the bubble surface with its image to the boundary. Our computations correlate well with experiments for both the first and second cycles of oscillation. The time history of the energy of a bubble system follows a step function, reducing rapidly and significantly because of emission of shock waves at inception of a bubble and at the end of collapse but remaining approximately constant for the rest of the time. The bubble starts being in near contact with the boundary during the first cycle of oscillation when the dimensionless stand-off distance γ = s/Rm < 1, where s is the distance of the initial bubble centre from the boundary and Rm is the maximum bubble radius. This leads to (i) the direct impact of a high-speed liquid jet on the boundary once it penetrates through the bubble, (ii) the direct contact of the bubble at high temperature and high pressure with the boundary, and (iii) the direct impingement of shock waves on the boundary once emitted. These phenomena have clear potential to damage the boundary, which are believed to be part of the mechanisms of cavitation damage. PMID:26442148

A novel technique for finding gas bubbles in the nuclear waste containers using Muon Scattering Tomography

NASA Astrophysics Data System (ADS)

Dobrowolska, M.; Velthuis, J.; Frazão, L.; Kikoła, D.

2018-05-01

Nuclear waste is deposited for many years in the concrete or bitumen-filled containers. With time hydrogen gas is produced, which can accumulate in bubbles. These pockets of gas may result in bitumen overflowing out of the waste containers and could result in spread of radioactivity. Muon Scattering Tomography is a non-invasive scanning method developed to examine the unknown content of nuclear waste drums. Here we present a method which allows us to successfully detect bubbles larger than 2 litres and determine their size with a relative uncertainty resolution of 1.55 ± 0.77%. Furthermore, the method allows to make a distinction between a conglomeration of bubbles and a few smaller gas volumes in different locations.

Simulating the universe(s) III: observables for the full bubble collision spacetime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Matthew C.; Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5; Wainwright, Carroll L.

2016-07-14

This is the third paper in a series establishing a quantitative relation between inflationary scalar field potential landscapes and the relic perturbations left by the collision between bubbles produced during eternal inflation. We introduce a new method for computing cosmological observables from numerical relativity simulations of bubble collisions in one space and one time dimension. This method tiles comoving hypersurfaces with locally-perturbed Friedmann-Robertson-Walker coordinate patches. The method extends previous work, which was limited to the spacetime region just inside the future light cone of the collision, and allows us to explore the full bubble-collision spacetime. We validate our new methodsmore » against previous work, and present a full set of predictions for the comoving curvature perturbation and local negative spatial curvature produced by identical and non-identical bubble collisions, in single scalar field models of eternal inflation. In both collision types, there is a non-zero contribution to the spatial curvature and cosmic microwave background quadrupole. Some collisions between non-identical bubbles excite wall modes, giving extra structure to the predicted temperature anisotropies. We comment on the implications of our results for future observational searches. For non-identical bubble collisions, we also find that the surfaces of constant field can readjust in the presence of a collision to produce spatially infinite sections that become nearly homogeneous deep into the region affected by the collision. Contrary to previous assumptions, this is true even in the bubble into which the domain wall is accelerating.« less

Reference intervals for selected serum biochemistry analytes in cheetahs Acinonyx jubatus.

PubMed

Hudson-Lamb, Gavin C; Schoeman, Johan P; Hooijberg, Emma H; Heinrich, Sonja K; Tordiffe, Adrian S W

2016-02-26

Published haematologic and serum biochemistry reference intervals are very scarce for captive cheetahs and even more for free-ranging cheetahs. The current study was performed to establish reference intervals for selected serum biochemistry analytes in cheetahs. Baseline serum biochemistry analytes were analysed from 66 healthy Namibian cheetahs. Samples were collected from 30 captive cheetahs at the AfriCat Foundation and 36 free-ranging cheetahs from central Namibia. The effects of captivity-status, age, sex and haemolysis score on the tested serum analytes were investigated. The biochemistry analytes that were measured were sodium, potassium, magnesium, chloride, urea and creatinine. The 90% confidence interval of the reference limits was obtained using the non-parametric bootstrap method. Reference intervals were preferentially determined by the non-parametric method and were as follows: sodium (128 mmol/L - 166 mmol/L), potassium (3.9 mmol/L - 5.2 mmol/L), magnesium (0.8 mmol/L - 1.2 mmol/L), chloride (97 mmol/L - 130 mmol/L), urea (8.2 mmol/L - 25.1 mmol/L) and creatinine (88 µmol/L - 288 µmol/L). Reference intervals from the current study were compared with International Species Information System values for cheetahs and found to be narrower. Moreover, age, sex and haemolysis score had no significant effect on the serum analytes in this study. Separate reference intervals for captive and free-ranging cheetahs were also determined. Captive cheetahs had higher urea values, most likely due to dietary factors. This study is the first to establish reference intervals for serum biochemistry analytes in cheetahs according to international guidelines. These results can be used for future health and disease assessments in both captive and free-ranging cheetahs.

Driving bubbles out of glass

NASA Technical Reports Server (NTRS)

Mattox, D. M.

1981-01-01

Surface tension gradient in melt forces gas bubbles to surface, increasing glass strength and transparency. Conventional chemical and buoyant fining are extremely slow in viscous glasses, but tension gradient method moves 250 um bubbles as rapidly as 30 um/s. Heat required for high temperature part of melt is furnished by stationary electrical or natural-gas heater; induction and laser heating are also possible. Method has many applications in industry processes.

Experimental and numerical study on bubble-sphere interaction near a rigid wall

NASA Astrophysics Data System (ADS)

Li, S.; Zhang, A. M.; Han, R.; Liu, Y. Q.

2017-09-01

This study is concerned with the interaction between a violently oscillating bubble and a movable sphere with comparable size near a rigid wall, which is an essential physical phenomenon in many applications such as cavitation, underwater explosion, ultrasonic cleaning, and biomedical treatment. Experiments are performed in a cubic water tank, and the underwater electric discharge technique (580 V DC) is employed to generate a bubble that is initiated between a rigid wall and a sphere in an axisymmetric configuration. The bubble-sphere interactions are captured using a high-speed camera operating at 52 000 frames/s. A classification of the bubble-sphere interaction is proposed, i.e., "weak," "intermediate," and "strong" interactions, identified with three distinct bubble shapes at the maximum volume moment. In the numerical simulations, the boundary integral method and the auxiliary function method are combined to establish a full coupling model that decouples the mutual dependence between the force and the sphere motion. The main features of bubble dynamics in different experiments are well reproduced by our numerical model. Meanwhile, the pressure and velocity fields are also provided for clarifying the associated mechanisms. The effects of two dimensionless standoff parameters, namely, γs (defined as ds/Rm, where ds is the minimum distance between the initial bubble center and the sphere surface and Rm is the maximum bubble radius) and γw (defined as dw/Rm, where dw is the distance between the initial bubble center and the rigid wall), are also discussed.

Compressible bubbles in Stokes flow

NASA Astrophysics Data System (ADS)

Crowdy, Darren G.

2003-02-01

The problem of a two-dimensional inviscid compressible bubble evolving in Stokes flow is considered. By generalizing the work of Tanveer & Vasconcelos (1995) it is shown that for certain classes of initial condition the quasi-steady free boundary problem for the bubble shape evolution is reducible to a finite set of coupled nonlinear ordinary differential equations, the form of which depends on the equation of state governing the relationship between the bubble pressure and its area. Recent numerical calculations by Pozrikidis (2001) using boundary integral methods are retrieved and extended. If the ambient pressures are small enough, it is shown that bubbles can expand significantly. It is also shown that a bubble evolving adiabatically is less likely to expand than an isothermal bubble.

Mesoporous hollow spheres from soap bubbling.

PubMed

Yu, Xianglin; Liang, Fuxin; Liu, Jiguang; Lu, Yunfeng; Yang, Zhenzhong

2012-02-01

The smaller and more stable bubbles can be generated from the large parent bubbles by rupture. In the presence of a bubble blowing agent, hollow spheres can be prepared by bubbling a silica sol. Herein, the trapped gas inside the bubble acts as a template. When the porogen, i.e., other surfactant, is introduced, a mesostructured shell forms by the co-assembly with the silica sol during sol-gel process. Morphological evolution emphasizes the prerequisite of an intermediate interior gas flow rate and high exterior gas flow rate for hollow spheres. The method is valid for many compositions from inorganic, polymer to their composites. Copyright © 2011 Elsevier Inc. All rights reserved.

Light Scattering by Ice Crystals Containing Air Bubbles

NASA Astrophysics Data System (ADS)

Zhang, J.; Panetta, R. L.; Yang, P.; Bi, L.

2014-12-01

The radiative effects of ice clouds are often difficult to estimate accurately, but are very important for interpretation of observations and for climate modeling. Our understanding of these effects is primarily based on scattering calculations, but due to the variability in ice habit it is computationally difficult to determine the required scattering and absorption properties, and the difficulties are only compounded by the need to include consideration of air and carbon inclusions of the sort frequently observed in collected samples. Much of the previous work on effects of inclusions in ice particles on scattering properties has been conducted with variants of geometric optics methods. We report on simulations of scattering by ice crystals with enclosed air bubbles using the pseudo-spectral time domain method (PSTD) and improved geometric optics method (IGOM). A Bouncing Ball Model (BBM) is proposed as a parametrization of air bubbles, and the results are compared with Monte Carlo radiative transfer calculations. Consistent with earlier studies, we find that air inclusions lead to a smoothing of variations in the phase function, weakening of halos, and a reduction of backscattering. We extend these studies by examining the effects of the particular arrangement of a fixed number of bubbles, as well as the effects of splitting a given number of bubbles into a greater number of smaller bubbles with the same total volume fraction. The result shows that the phase function will not change much for stochastic distributed air bubbles. It also shows that local maxima of phase functions are smoothed out for backward directions, when we break bubbles into small ones, single big bubble scatter favors more forward scattering than multi small internal scatters.

GASTROINTESTINAL PARASITES IN CAPTIVE AND FREE-RANGING BIRDS AND POTENTIAL CROSS-TRANSMISSION IN A ZOO ENVIRONMENT.

PubMed

Carrera-Játiva, Patricio D; Morgan, Eric R; Barrows, Michelle; Wronski, Torsten

2018-03-01

Gastrointestinal parasites are commonly reported in wild birds, but transmission amongst avifauna in zoological settings, and between these captive birds and wild birds in surrounding areas, remains poorly understood. A survey was undertaken to investigate the occurrence of gastrointestinal parasites in captive and free-ranging birds at Bristol Zoo Gardens between May and July 2016. A total of 348 fecal samples from 32 avian species were examined using the Mini-FLOTAC flotation method. Parasites were detected in 31% (45/145) of samples from captive birds and in 65.5% (133/203) of samples from free-ranging birds. Parasites of captive individuals included ascarids ( Heterakis spp. and other morphotypes), capillarids, oxyurids, strongyles, a trematode, and protozoans ( Eimeria spp., Isospora spp., Caryospora sp., and Entamoeba spp.). Parasites of free-ranging birds included ascarids ( Ascaridia spp., Porrocaecum spp., and other morphotypes), capillarids, oxyurids, strongyles ( Syngamus spp. and other morphotypes), cestodes ( Choanotaenia spp., Hymenolepis spp., and other morphotypes), a trematode, and protozoans ( Eimeria spp., Isospora spp., Entamoeba spp.). Similar types of parasites were detected in captive and free-ranging birds, but capillarid ova morphology was similar only between closely related species, eg in corvids (captive azure-winged magpies [ Cyanipica cyana] and wild jackdaws [ Corvus monedula]) and between wild columbids (collared doves [ Streptopelia decaocto], rock doves [ Columba livia], and wood pigeons [ Columba palumbus]). The prevalence and intensity of nematodes and coccidia in birds housed outdoors did not differ statistically from species housed indoors. Results indicate that captive and free-ranging birds may share parasites when closely related, but this would need to be confirmed by the study of adult specimens and molecular tests. Determining which parasites are present in captive and free-ranging species in zoological parks will support the establishment of effective husbandry practices to maintain the health status of managed species.

Benefits of polidocanol endovenous microfoam (Varithena®) compared with physician-compounded foams.

PubMed

Carugo, Dario; Ankrett, Dyan N; Zhao, Xuefeng; Zhang, Xunli; Hill, Martyn; O'Byrne, Vincent; Hoad, James; Arif, Mehreen; Wright, David D I; Lewis, Andrew L

2016-05-01

To compare foam bubble size and bubble size distribution, stability, and degradation rate of commercially available polidocanol endovenous microfoam (Varithena®) and physician-compounded foams using a number of laboratory tests. Foam properties of polidocanol endovenous microfoam and physician-compounded foams were measured and compared using a glass-plate method and a Sympatec QICPIC image analysis method to measure bubble size and bubble size distribution, Turbiscan™ LAB for foam half time and drainage and a novel biomimetic vein model to measure foam stability. Physician-compounded foams composed of polidocanol and room air, CO2, or mixtures of oxygen and carbon dioxide (O2:CO2) were generated by different methods. Polidocanol endovenous microfoam was found to have a narrow bubble size distribution with no large (>500 µm) bubbles. Physician-compounded foams made with the Tessari method had broader bubble size distribution and large bubbles, which have an impact on foam stability. Polidocanol endovenous microfoam had a lower degradation rate than any physician-compounded foams, including foams made using room air (p < 0.035). The same result was obtained at different liquid to gas ratios (1:4 and 1:7) for physician-compounded foams. In all tests performed, CO2 foams were the least stable and different O2:CO2 mixtures had intermediate performance. In the biomimetic vein model, polidocanol endovenous microfoam had the slowest degradation rate and longest calculated dwell time, which represents the length of time the foam is in contact with the vein, almost twice that of physician-compounded foams using room air and eight times better than physician-compounded foams prepared using equivalent gas mixes. Bubble size, bubble size distribution and stability of various sclerosing foam formulations show that polidocanol endovenous microfoam results in better overall performance compared with physician-compounded foams. Polidocanol endovenous microfoam offers better stability and cohesive properties in a biomimetic vein model compared to physician-compounded foams. Polidocanol endovenous microfoam, which is indicated in the United States for treatment of great saphenous vein system incompetence, provides clinicians with a consistent product with enhanced handling properties. © The Author(s) 2015.

Investigation of system integration methods for bubble domain flight recorders

NASA Technical Reports Server (NTRS)

Chen, T. T.; Bohning, O. D.

1975-01-01

System integration methods for bubble domain flight records are investigated. Bubble memory module packaging and assembly, the control electronics design and construction, field coils, and permanent magnet bias structure design are studied. A small 60-k bit engineering model was built and tested to demonstrate the feasibility of the bubble recorder. Based on the various studies performed, a projection is made on a 50,000,000-bit prototype recorder. It is estimated that the recorder will occupy 190 cubic in., weigh 12 lb, and consume 12 w power when all of its four tracks are operated in parallel at 150 kHz data rate.

Bubble nucleation in simple and molecular liquids via the largest spherical cavity method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonzalez, Miguel A., E-mail: m.gonzalez12@imperial.ac.uk; Department of Chemistry, Imperial College London, London SW7 2AZ; Abascal, José L. F.

2015-04-21

In this work, we propose a methodology to compute bubble nucleation free energy barriers using trajectories generated via molecular dynamics simulations. We follow the bubble nucleation process by means of a local order parameter, defined by the volume of the largest spherical cavity (LSC) formed in the nucleating trajectories. This order parameter simplifies considerably the monitoring of the nucleation events, as compared with the previous approaches which require ad hoc criteria to classify the atoms and molecules as liquid or vapor. The combination of the LSC and the mean first passage time technique can then be used to obtain themore » free energy curves. Upon computation of the cavity distribution function the nucleation rate and free-energy barrier can then be computed. We test our method against recent computations of bubble nucleation in simple liquids and water at negative pressures. We obtain free-energy barriers in good agreement with the previous works. The LSC method provides a versatile and computationally efficient route to estimate the volume of critical bubbles the nucleation rate and to compute bubble nucleation free-energies in both simple and molecular liquids.« less

[Activity of the hypothalamo-pituitary-adrenals axis in the Siberian tiger (Panthera tigris altaica) in captivity and in the wild, and their dynamics throughout the year].

PubMed

Naidenko, S V; Ivanov, E A; Lukarevskiĭ, V S; Hernandez-Blanko, J A; Sorokin, P A; Litvinov, M N; Kotliar, A K; Rozhnov, V V

2011-01-01

A noninvasive evaluation method of hypothalamo-pituitary-adrenals axis (HPA) activity in the Siberian tiger was verified. Comparison of the activity level of HPA in Siberian tigers in the wild and in captivity, and their alterations over the year was carried out. Significant seasonal deviations between activity levels of HPA in tigers in captivity were not found. In the wild, this level was significantly higher, reaching the maximum from November to January, which can be related with an unfavorable influence on tigers in low temperatures and deep snow cover.

Fermi Bubbles: an elephant in the gamma-ray sky

NASA Astrophysics Data System (ADS)

Malyshev, Dmitry

2017-03-01

The Fermi bubbles are one of the most remarkable features in the gamma-ray sky revealed by the Fermi Large Area Telescope (LAT). The nature of the gamma-ray emission and the origin of the bubbles are still open questions. In this note, we will review some basic features of leptonic and hadronic modes of gamma-ray production. At the moment, gamma rays are our best method to study the bubbles, but in order to resolve the origin of the bubbles multi-wavelength and multi-messenger observations will be crucial.

Proposed method to estimate the liquid-vapor accommodation coefficient based on experimental sonoluminescence data.

PubMed

Puente, Gabriela F; Bonetto, Fabián J

2005-05-01

We used the temporal evolution of the bubble radius in single-bubble sonoluminescence to estimate the water liquid-vapor accommodation coefficient. The rapid changes in the bubble radius that occur during the bubble collapse and rebounds are a function of the actual value of the accommodation coefficient. We selected bubble radius measurements obtained from two different experimental techniques in conjunction with a robust parameter estimation strategy and we obtained that for water at room temperature the mass accommodation coefficient is in the confidence interval [0.217,0.329].

Soap bubbles in analytical chemistry. Conductometric determination of sub-parts per million levels of sulfur dioxide with a soap bubble.

PubMed

Kanyanee, Tinakorn; Borst, Walter L; Jakmunee, Jaroon; Grudpan, Kate; Li, Jianzhong; Dasgupta, Purnendu K

2006-04-15

Soap bubbles provide a fascinating tool that is little used analytically. With a very low liquid volume to surface area ratio, a soap bubble can potentially provide a very useful interface for preconcentration where mass transfer to an interfacial surface is important. Here we use an automated system to create bubbles of uniform size and film thickness. We utilize purified Triton-X 100, a nonionic surfactant, to make soap bubbles. We use such bubbles as a gas-sampling interface. Incorporating hydrogen peroxide into the bubble provides a system where electrical conductance increases as the bubble is exposed to low concentrations of sulfur dioxide gas. We theoretically derive the conductance of a hollow conducting spherical thin film with spherical cap electrodes. We measure the film thickness by incorporating a dye in the bubble making solution and laser transmission photometry and find that it agrees well with the geometrically computed thickness. With the conductance of the bubble-making soap solution being measured by conventional methods, we show that the measured values of the bubble conductance with known bubble and electrode dimensions closely correspond to the theoretically computed value. Finally, we demonstrate that sub-ppm levels of SO(2) can readily be detected by the conductivity change of a hydrogen peroxide-doped soap bubble, measured in situ, when the gas flows around the bubble.

Reintroduction and translocation of 'Oma'o: A comparison of methods

USGS Publications Warehouse

Fancy, Steven G.; Nelson, Jay T.; Harrity, Peter; Kuhn, Jope; Kuhn, Marla; Kuehler, Cyndi; Giffin, Jon G.

2001-01-01

We reintroduced 25 captive-reared ‘Oma‘o (Myadestes obscurus) and translocated 16 wild-caught ‘Oma‘o to former range in the Pu‘u Wa‘awa‘a Wildlife Sanctuary on the island of Hawai‘i to develop and refine methods that might be used in the recovery of the closely related and critically endangered Puaiohi (Myadestes palmeri) on Kaua‘i. Captive-reared ‘Oma‘o were soft-released from two hacking towers at 66-57 days of age, whereas wild birds (all adults) were hard-released on the same day as capture or after a l-9 day holding period. The fate of all birds was monitored daily for two months using radiotelemetry. Only 16 of 76 (21%) wild-caught ‘Oma‘o were translocated because of problems with active avian poxlike lesions, an imbalanced sex ratio, or because birds would not eat during holding. Survival to 30 days post-release was similar for birds released by the two methods: three captive-reared ‘Oma‘o were killed by predators, and four wild ‘Oma‘o died of handling/transport stress. ‘Oma‘o populations are highly male biased, and a sex ratio of captive-hatched eggs of 18 males to 6 females suggests that the sex ratio may not be 1:1 at hatching. Translocation of hatching-year ‘Oma‘o would not be practical because of very low capture success for juvenile ‘Oma‘o and the skewed sex ratio. Fidelity to the release site was higher for captive-reared birds, and this approach is less expensive for ‘Oma‘o and more likely to result in successful establishment of a new population in continuous habitat.

Odds of observing the multiverse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahlen, A.

2010-03-15

Eternal inflation predicts that our observable universe lies within a bubble (or pocket universe) embedded in a volume of inflating space. The interior of the bubble undergoes inflation and standard cosmology, while the bubble walls expand outward and collide with other neighboring bubbles. The collisions provide either an opportunity to make a direct observation of the multiverse or, if they produce unacceptable anisotropy, a threat to inflationary theory. The probability of an observer in our bubble detecting the effects of collisions has an absolute upper bound set by the odds of being in the part of our bubble that liesmore » in the forward light cone of a collision; in the case of collisions with bubbles of identical vacua, this bound is given by the bubble nucleation rate times (H{sub O}/H{sub I}){sup 2}, where H{sub O} is the Hubble scale outside the bubbles and H{sub I} is the scale of the second round of inflation that occurs inside our bubble. Similar results were obtained by Freigovel et al. using a different method for the case of collisions with bubbles of much larger cosmological constant; here, it is shown to hold in the case of collisions with identical bubbles as well.« less

Study of a Novel Method for the Thermolysis of Solutes in Aqueous Solution Using a Low Temperature Bubble Column Evaporator.

PubMed

Shahid, Muhammad; Xue, Xinkai; Fan, Chao; Ninham, Barry W; Pashley, Richard M

2015-06-25

An enhanced thermal decomposition of chemical compounds in aqueous solution has been achieved at reduced solution temperatures. The technique exploits hitherto unrecognized properties of a bubble column evaporator (BCE). It offers better heat transfer efficiency than conventional heat transfer equipment. This is obtained via a continuous flow of hot, dry air bubbles of optimal (1-3 mm) size. Optimal bubble size is maintained by using the bubble coalescence inhibition property of some salts. This novel method is illustrated by a study of thermal decomposition of ammonium bicarbonate (NH4HCO3) and potassium persulfate (K2S2O8) in aqueous solutions. The decomposition occurs at significantly lower temperatures than those needed in bulk solution. The process appears to work via the continuous production of hot (e.g., 150 °C) dry air bubbles, which do not heat the solution significantly but produce a transient hot surface layer around each rising bubble. This causes the thermal decomposition of the solute. The decomposition occurs due to the effective collision of the solute with the surface of the hot bubbles. The new process could, for example, be applied to the regeneration of the ammonium bicarbonate draw solution used in forward osmosis.

A New 4D Imaging Method for Three-Phase Analogue Experiments in Volcanology (and Other Three-Phase Systems)

NASA Astrophysics Data System (ADS)

Oppenheimer, J.; Patel, K. B.; Lev, E.; Hillman, E. M. C.

2017-12-01

Bubbles and crystals suspended in magmas interact with each other on a small scale, which affects large-scale volcanic processes. Studying these interactions on relevant scales of time and space is a long-standing challenge. Therefore, the fundamental explanations for the behavior of bubble- and crystal-rich magmas are still largely speculative. Recent application of X-ray tomography to experiments with synthetic magmas has already improved our understanding of small-scale 4D (3D + time) phenomena. However, this technique has low imaging rates < 20 volumes per second (vps) and does not work well with analogues, making experiments costly and slow. We demonstrate a novel methodology for imaging bubble-particle interactions in analogue suspensions by utilizing Swept Confocally Aligned Planar Excitation (SCAPE) microscopy. This method based on laser-fluorescence has been used to image live biological processes at high speed and in 3D. It allows imaging rates of up to several hundred vps and image volumes up to 1 x 1 x 0.5 mm3, with a trade-off between speed and spatial resolution. We ran two sets of experiments with silicone oil and soda-lime glass beads of <50 µm diameter, contained within a vertical glass casing 50 x 5 x 4 mm3. We used two different bubble generation methods. In the first set of experiments, small air bubbles (< 1 mm) were introduced through a hole at the bottom of the sample and allowed to rise through a suspension with low-viscosity oil. We successfully imaged bubble rise and particle movements around the bubble. In the second set, bubbles were generated by mixing acetone into the suspension and decreasing the surface pressure to cause a phase change to gaseous acetone. This bubble generation method compared favorably with previous gum rosin-acetone experiments: they provided similar degassing behaviors, along with more control on suspension viscosity and optimal optical properties for laser transmission. Large volumes of suspended bubbles, however, interfered with the laser path. In this set, we were able to track bubble nucleation sites and nucleation rates in 4D. This promising technique allows the study of small-scale interactions in two- and three-phase systems, at high imaging rates and at low cost.

Interaction mechanism of double bubbles in hydrodynamic cavitation

NASA Astrophysics Data System (ADS)

Li, Fengchao; Cai, Jun; Huai, Xiulan; Liu, Bin

2013-06-01

Bubble-bubble interaction is an important factor in cavitation bubble dynamics. In this paper, the dynamic behaviors of double cavitation bubbles driven by varying pressure field downstream of an orifice plate in hydrodynamic cavitation reactor are examined. The bubble-bubble interaction between two bubbles with different radii is considered. We have shown the different dynamic behaviors between double cavitation bubbles and a single bubble by solving two coupling nonlinear equations using the Runge-Kutta fourth order method with adaptive step size control. The simulation results indicate that, when considering the role of the neighbor smaller bubble, the oscillation of the bigger bubble gradually exhibits a lag in comparison with the single-bubble case, and the extent of the lag becomes much more obvious as time goes by. This phenomenon is more easily observed with the increase of the initial radius of the smaller bubble. In comparison with the single-bubble case, the oscillation of the bigger bubble is enhanced by the neighbor smaller bubble. Especially, the pressure pulse of the bigger bubble rises intensely when the sizes of two bubbles approach, and a series of peak values for different initial radii are acquired when the initial radius ratio of two bubbles is in the range of 0.9˜1.0. Although the increase of the center distance between two bubbles can weaken the mutual interaction, it has no significant influence on the enhancement trend. On the one hand, the interaction between two bubbles with different radii can suppress the growth of the smaller bubble; on the other hand, it also can enhance the growth of the bigger one at the same time. The significant enhancement effect due to the interaction of multi-bubbles should be paid more attention because it can be used to reinforce the cavitation intensity for various potential applications in future.

Nonlinear interaction between underwater explosion bubble and structure based on fully coupled model

NASA Astrophysics Data System (ADS)

Zhang, A. M.; Wu, W. B.; Liu, Y. L.; Wang, Q. X.

2017-08-01

The interaction between an underwater explosion bubble and an elastic-plastic structure is a complex transient process, accompanying violent bubble collapsing, jet impact, penetration through the bubble, and large structural deformation. In the present study, the bubble dynamics are modeled using the boundary element method and the nonlinear transient structural response is modeled using the explicit finite element method. A new fully coupled 3D model is established through coupling the equations for the state variables of the fluid and structure and solving them as a set of coupled linear algebra equations. Based on the acceleration potential theory, the mutual dependence between the hydrodynamic load and the structural motion is decoupled. The pressure distribution in the flow field is calculated with the Bernoulli equation, where the partial derivative of the velocity potential in time is calculated using the boundary integral method to avoid numerical instabilities. To validate the present fully coupled model, the experiments of small-scale underwater explosion near a stiffened plate are carried out. High-speed imaging is used to capture the bubble behaviors and strain gauges are used to measure the strain response. The numerical results correspond well with the experimental data, in terms of bubble shapes and structural strain response. By both the loosely coupled model and the fully coupled model, the interaction between a bubble and a hollow spherical shell is studied. The bubble patterns vary with different parameters. When the fully coupled model and the loosely coupled model are advanced with the same time step, the error caused by the loosely coupled model becomes larger with the coupling effect becoming stronger. The fully coupled model is more stable than the loosely coupled model. Besides, the influences of the internal fluid on the dynamic response of the spherical shell are studied. At last, the case that the bubble interacts with an air-backed stiffened plate is simulated. The associated interesting physical phenomenon is obtained and expounded.

Effect of the Inhomogeneity of Ice Crystals on Retrieving Ice Cloud Optical Thickness and Effective Particle Size

NASA Technical Reports Server (NTRS)

Xie, Yu; Minnis, Patrick; Hu, Yong X.; Kattawar, George W.; Yang, Ping

2008-01-01

Spherical or spheroidal air bubbles are generally trapped in the formation of rapidly growing ice crystals. In this study the single-scattering properties of inhomogeneous ice crystals containing air bubbles are investigated. Specifically, a computational model based on an improved geometric-optics method (IGOM) has been developed to simulate the scattering of light by randomly oriented hexagonal ice crystals containing spherical or spheroidal air bubbles. A combination of the ray-tracing technique and the Monte Carlo method is used. The effect of the air bubbles within ice crystals is to smooth the phase functions, diminish the 22deg and 46deg halo peaks, and substantially reduce the backscatter relative to bubble-free particles. These features vary with the number, sizes, locations and shapes of the air bubbles within ice crystals. Moreover, the asymmetry factors of inhomogeneous ice crystals decrease as the volume of air bubbles increases. Cloud reflectance lookup tables were generated at wavelengths 0.65 m and 2.13 m with different air-bubble conditions to examine the impact of the bubbles on retrieving ice cloud optical thickness and effective particle size. The reflectances simulated for inhomogeneous ice crystals are slightly larger than those computed for homogenous ice crystals at a wavelength of 0.65 microns. Thus, the retrieved cloud optical thicknesses are reduced by employing inhomogeneous ice cloud models. At a wavelength of 2.13 microns, including air bubbles in ice cloud models may also increase the reflectance. This effect implies that the retrieved effective particle sizes for inhomogeneous ice crystals are larger than those retrieved for homogeneous ice crystals, particularly, in the case of large air bubbles.

Effects of floc and bubble size on the efficiency of the dissolved air flotation (DAF) process.

PubMed

Han, Mooyoung; Kim, Tschung-il; Kim, Jinho

2007-01-01

Dissolved air flotation (DAF) is a method for removing particles from water using micro bubbles instead of settlement. The process has proved to be successful and, since the 1960s, accepted as an alternative to the conventional sedimentation process for water and wastewater treatment. However, limited research into the process, especially the fundamental characteristics of bubbles and particles, has been carried out. The single collector collision model is not capable of determining the effects of particular characteristics, such as the size and surface charge of bubbles and particles. Han has published a set of modeling results after calculating the collision efficiency between bubbles and particles by trajectory analysis. His major conclusion was that collision efficiency is maximum when the bubbles and particles are nearly the same size but have opposite charge. However, experimental verification of this conclusion has not been carried out yet. This paper describes a new method for measuring the size of particles and bubbles developed using computational image analysis. DAF efficiency is influenced by the effect of the recycle ratio on various average floc sizes. The larger the recycle ratio, the higher the DAF efficiency at the same pressure and particle size. The treatment efficiency is also affected by the saturation pressure, because the bubble size and bubble volume concentration are controlled by the pressure. The highest efficiency is obtained when the floc size is larger than the bubble size. These results, namely that the highest collision efficiency occurs when the particles and bubbles are about the same size, are more in accordance with the trajectory model than with the white water collector model, which implies that the larger the particles, the higher is the collision efficiency.

Hormonal induction of spawning in 4 species of frogs by coinjection with a gonadotropin-releasing hormone agonist and a dopamine antagonist

PubMed Central

2010-01-01

Background It is well known that many anurans do not reproduce easily in captivity. Some methods are based on administration of mammalian hormones such as human chorionic gonadotropin, which are not effective in many frogs. There is a need for simple, cost-effective alternative techniques to induce spawning. Methods Our new method is based on the injection of a combination of a gonadotropin-releasing hormone (GnRH) agonist and a dopamine antagonist. We have named this formulation AMPHIPLEX, which is derived from the combination of the words amphibian and amplexus. This name refers to the specific reproductive behavior of frogs when the male mounts and clasps the female to induce ovulation and to fertilize the eggs as they are laid. Results We describe the use of the method and demonstrate its applicability for captive breeding in 3 different anuran families. We tested several combinations of GnRH agonists with dopamine antagonists using Lithobates pipiens. The combination of des-Gly10, D-Ala6, Pro-LHRH (0.4 microrams/g body weight) and metoclopramide (10 micrograms/g BWt. MET) was most effective. It was used in-season, after short-term captivity and in frogs artificially hibernated under laboratory conditions. The AMPHIPLEX method was also effective in 3 Argentinian frogs, Ceratophrys ornata, Ceratophrys cranwelli and Odontophrynus americanus. Conclusion Our approach offers some advantages over other hormonally-based techniques. Both sexes are injected only once and at the same time, reducing handling stress. AMPHIPLEX is a new reproductive management tool for captive breeding in Anura. PMID:20398399

Mass Transport Phenomena Between Bubbles and Dissolved Gases in Liquids Under Reduced Gravity Conditions

NASA Technical Reports Server (NTRS)

Dewitt, K. J.; Brockwell, J. L.

1985-01-01

The long term objective of the experiment is to observe the dissolution of isolated, immobile gas bubbles of specified size and composition in a solvent liquid of known concentration in the reduced gravity environment of earth orbit. Preliminary bubble dissolution experiment conducted both in the NASA Lewis 2.2 sec drop tower and in normal gravity using SO2 - Toluene system were not completely successful in their objective. The method of gas injection and lack of bubble interface stabiliy experienced due to the extreme solubility of SO in Toluene has the effects of changing the problem from that of bubble dissolution to one of bubble formation stability and subsequent dissolution in a liquid of unknown initial solute concentration. Current work involves further experimentation in order to refine the bubble injection system and to investigate the concept of having a bubble with a critical radius in a state of unstable equilibrium.

Reversible switch between underwater superaerophilicity and superaerophobicity on the superhydrophobic nanowire-haired mesh for controlling underwater bubble wettability

NASA Astrophysics Data System (ADS)

Shan, Chao; Yong, Jiale; Yang, Qing; Chen, Feng; Huo, Jinglan; Zhuang, Jian; Jiang, Zhuangde; Hou, Xun

2018-04-01

Controlling the underwater bubble wettability on a solid surface is of great research significance. In this letter, a simple method to achieve reversible switch between underwater superaerophilicity and underwater superaerophobicity on a superhydrophobic nanowire-haired mesh by alternately vacuumizing treatment in water and drying in air is reported. Such reversible switch endows the as-prepared mesh with many functional applications in controlling bubble's behavior on a solid substrate. The underwater superaerophilic mesh is able to absorb/capture bubbles in water, while the superaerophobic mesh has great anti-bubble ability. The reversible switch between underwater superaerophilicity and superaerophobicity can selectively allow bubbles to go through the resultant mesh; that is, bubbles can pass through the underwater superaerophilic mesh while are fully intercepted by the underwater superaerophobic mesh in a water medium. We believe these meshes will have important applications in removing or capturing underwater bubbles/gas.

Numerical analysis of bubble-cluster formation in an ultrasonic field

NASA Astrophysics Data System (ADS)

Kim, Donghyun; Son, Gihun

2016-11-01

Bubble-cluster formation in an ultrasonic field is investigated numerically solving the conservation equations of mass, momentum and energy. The liquid-gas interface is calculated using the volume-of-fluid method with variable gas density to consider the bubble compressibility. The effect of liquid-gas phase change is also included as the interface source terms of the mass and energy equations. The numerical approach is tested through the simulation of the expansion and contraction motion of a compressed bubble adjacent to a wall. When the bubble is placed in an ultrasonic field, it oscillates radially and then collapses violently. Numerical simulation is also performed for bubble-cluster formation induced by an ultrasonic generator, where the generated bubbles are merged into a macrostructure along the acoustic flow field. The effects of ultrasonic power and frequency, liquid properties and pool temperature on the bubble-cluster formation are investigated. This work was supported by the Korea Institute of Energy Research.

Dual-frequency ultrasound for detecting and sizing bubbles.

PubMed

Buckey, Jay C; Knaus, Darin A; Alvarenga, Donna L; Kenton, Marc A; Magari, Patrick J

2005-01-01

ISS construction and Mars exploration require extensive extravehicular activity (EVA), exposing crewmembers to increased decompression sickness risk. Improved bubble detection technologies could help increase EVA efficiency and safety. Creare Inc. has developed a bubble detection and sizing instrument using dual-frequency ultrasound. The device emits "pump" and "image" signals at two frequencies. The low-frequency pump signal causes an appropriately-sized bubble to resonate. When the image frequency hits a resonating bubble, mixing signals are returned at the sum and difference of the two frequencies. To test the feasibility of transcutaneous intravascular detection, intravascular bubbles in anesthetized swine were produced using agitated saline and decompression stress. Ultrasonic transducers on the chest provided the two frequencies. Mixing signals were detected transthoracically in the right atrium using both methods. A histogram of estimated bubble sizes could be constructed. Bubbles can be detected and sized transthoracically in the right atrium using dual-frequency ultrasound. c2005 Elsevier Ltd. All rights reserved.

Characterisation of bubbles in liquids using acoustic techniques

NASA Astrophysics Data System (ADS)

Ramble, David Gary

1997-12-01

This thesis is concerned with the characterisation of air bubbles in a liquid through the use of a range of acoustic techniques, with the ultimate aim of minimising the ambiguity of the result and the complexity of the task. A bubble is particularly amenable to detection by using acoustical methods because there usually exists a large acoustic impedance mismatch between the gas/vapour inside the bubble and that of the surrounding liquid. The bubble also behaves like a single degree-of-freedom oscillator when excited, and as such exhibits a well-defined resonance frequency which is related to its radius. Though techniques which exploit this resonance property of the bubble are straightforward to apply, the results are prone to ambiguities as larger bubbles can geometrically scatter more sound than a smaller resonant bubble. However, these drawbacks can be overcome by using acoustical methods which make use of the nonlinear behaviour of bubbles. A particular nonlinear technique monitors the second harmonic emission of the bubble which is a global maximum at resonance. In addition, a two- frequency excitation technique is used which involves exciting the bubble with a fixed high frequency signal (the imaging signal, ωi) of the order of megahertz, and a lower variable frequency (the pumping signal, ωp) which is tuned to the bubble's resonance. The bubble couples these two sound fields together to produce sum-and-difference terms which peak at resonance. The two most promising combination frequency signals involve the coupling of the bubble's fundamental with the imaging frequency to give rise to a ωi+ωp signal, and the coupling of a subharmonic signal at half the resonance frequency of the bubble to give rise to a ωi/pmωp/2 signal. Initially, theory is studied which outlines the advantages and disadvantages of each of the acoustic techniques available. Experiments are then conducted in a large tank of water on simple bubble populations, ranging from stationary single and paired bubbles, to a single rising bubble stream. The techniques are first applied sequentially for calibration purposes and then a selection are applied simultaneously to enable a direct comparison of these methods. Following this, the techniques are applied to the more challenging and practical acoustic environment of a fluid-filled pipe, where the first experimental measurement in a pipe of the ωi/pm ωp/2 signal is obtained. The mechanisms and theory responsible for the optimal acoustic techniques are then investigated further, where it is shown that the ωi/pm ωp signal is a particularly robust signal, whereas the ωi/pmωp/2 signal's main drawback is related to its parametric nature. This last point is demonstrated by the very good agreement obtained when comparing the experimentally measured ωi/pmωp/2 threshold with the onset threshold for surface waves set-up around the bubble wall, calculated using surface-wave theory derived for spherical surfaces. Therefore, because of its greater reliability (with respect to repeatability and lack of ambiguity) compared to all the other monitored signals (ωp,/ 2ωp,/ ωp/2,/ ωp,/ ωi/pm 2ωp and ωi/pm ωp/2), the ωi/pmωp signal was chosen to investigate for the first time the bubble population in the surf zone. Finally, from the results of the sea trials and the laboratory results an optimal bubble sizing methodology is given where the limitations of one technique can find compensation in the deployment of another.

A variational approach to the strongly nonlinear regime of the Rayleigh-Taylor instability

NASA Astrophysics Data System (ADS)

Yoshikawa, Toshio

The Rayleigh-Taylor instability is the instability of the interface between two fluids of different densities. When a heavy fluid is superposed over a light fluid. small disturbances on the interface develop into a complex form with heavy fluid ``fingers'' and light fluid ``bubbles.'' We propose a variational method for the description of the evolution of the fingers and bubbles in the late stage of the instability. In this method, the fluid region is represented as the image of a time-dependent conformal mapping; the dynamics of the mapping is determined by the least action principle for the Lagrangian. i.e., the kinetic energy minus the potential energy. The evolution of a single finger and bubble is investigated by this method. We first consider a symmetric finger and bubble in a zero gravitational field. We derive an integrable Hamiltonian system with two degrees of freedom that governs the dynamics of the symmetric finger and bubble. We present a general solution of the system. The solution predicts the linear growth of the finger and the saturation of the bubble growth. It is shown that this solution is asymptotically exact. We consider a symmetric finger and bubble with perturbations. We show that the dynamics of the finger and bubble and that of the perturbations are decoupled. We next consider an inclined finger and bubble in a zero gravitational field. We derive a Hamiltonian system with four degrees of freedom that governs the dynamics of the inclined finger and bubble. The system has four integrals of motion, one of them depends on time explicitly. When there is no lateral motion, the system reduces to an integrable Hamiltonian system with three degrees of freedom. A general solution of the system is presented. The solution predicts the linear growth of the finger toward a direction and the saturation of the bubble growth. Finally, we consider a symmetric finger and bubble in a uniform gravitational field. We derive a Hamiltonian system with two degrees of freedom that governs the dynamics of the symmetric finger and bubble. Since the system includes a potential energy term, it is not integrable in general. However, we present a general solution in the case of the total energy being zero. This case corresponds to an interesting case where the evolution starts from a flat surface. The solution predicts that the finger grows as the square of time, and the bubble as the square root of time.

Probing He bubbles in naturally aged and annealed δ-Pu alloys using ultra-small-angle x-ray scattering

DOE PAGES

Jeffries, J. R.; Hammons, J. A.; Willey, T. M.; ...

2017-10-31

We report the self-irradiation of Pu alloys generates He that is trapped within the metal matrix in the form of He bubbles. The distribution of these He bubbles in δ-phase Pu-Ga alloys exhibits a peak near a radius of 0.7 nm, and this size is remarkably stable as function of time. When annealed, the He bubbles in δ-Pu alloys grow, coarsening the distribution. However, the magnitude of this coarsening is uncertain, as different experimental methods reveal bubbles that differ by at least one order of magnitude. Small-angle x-ray scattering results, which can probe a wide range of bubble sizes, implymore » only a mild coarsening of the He bubble distribution for an annealing treatment of 425 °C for 24 h, and analysis of the He bubble content suggests that He is actually lost from the bubbles with annealing.« less

Size limits the formation of liquid jets during bubble bursting

PubMed Central

Lee, Ji San; Weon, Byung Mook; Park, Su Ji; Je, Jung Ho; Fezzaa, Kamel; Lee, Wah-Keat

2011-01-01

A bubble reaching an air–liquid interface usually bursts and forms a liquid jet. Jetting is relevant to climate and health as it is a source of aerosol droplets from breaking waves. Jetting has been observed for large bubbles with radii of R≫100 μm. However, few studies have been devoted to small bubbles (R<100 μm) despite the entrainment of a large number of such bubbles in sea water. Here we show that jet formation is inhibited by bubble size; a jet is not formed during bursting for bubbles smaller than a critical size. Using ultrafast X-ray and optical imaging methods, we build a phase diagram for jetting and the absence of jetting. Our results demonstrate that jetting in bubble bursting is analogous to pinching-off in liquid coalescence. The coalescence mechanism for bubble bursting may be useful in preventing jet formation in industry and improving climate models concerning aerosol production. PMID:21694715

Resonant Frequency Shifts of a Fluid Filled Cavity Caused by a Bubble

NASA Astrophysics Data System (ADS)

Zhang, Hailan; Wang, Xiuming; Chen, Dehua; Che, Chengxuan

2009-03-01

In the previous studies for estimating acoustic wave velocities and attenuations of a rock specimen in a low frequency range using an acoustic resonance spectroscopy method, it was found that bubbles in a fluid filled cavity reduce the resonant frequency of the cavity significantly, which makes the measurement unstable. In this paper, this phenomenon is explained by using a simple model of a spherical fluid filled cavity with a single air bubble. It is pointed out that air bubble effects are caused by the vibration of the bubble coupled with the vibration of the cavity and, therefore, the measurement must be carefully prepared to prevent any air bubbles from entering the cavity.

Captive and field-tested radio attachments for bald eagles

USGS Publications Warehouse

Buehler, D.A.; Fraser, J.D.; Fuller, M.R.; McAllister, L.S.; Seegar, J.K.D.

1995-01-01

The effects of two radio transmitter attachment techniques on captive and one attachment technique on wild Bald Eagles (Haliaeetus leucocephalus) were studied. A Y-attachment method with a 160-g dummy transmitter was less apt to cause tissue damage on captive birds than an X-attachment method, and loosely fit transmitters caused less damage than tightly fit transmitters Annual survival of wild birds fitted with 65-g transmitters via an X attachment was estimated at 90-95%. As a result of high survival, only five wild birds marked as nestlings were recovered.Two of these birds had superficial pressure sores from tight-fitting harnesses It is recommended that a 1.3-cm space be left between the transmitter and the bird's b ack when radio-tagging post-fiedging Bald Eagles. Additional space, perhaps up to 2.5 cm, is required for nestlings to allow for added growth and development.

Investigation of the interaction dynamics of a pair of laser-induced bubbles generated at the same time through double-exposure strobe method and numerical simulations

NASA Astrophysics Data System (ADS)

Han, Bing; Liu, Liu; Ni, Xiao-Wu

2017-08-01

In order to understand the interaction dynamics of a pair of laser-induced bubbles, a double-exposure strobe photography experimental setup is build up to study the temporal evolution of the bubble pairs and to measure the transient bubble-interface moving speed. The interaction mechanisms of the bubble pairs are discussed together with the numerical results obtained through OpenFOAM. It is shown that the direction and the velocity of the jetting could be controlled by the relative size and the relative initiation distance of the bubble pair, when the bubbles are generated at the same time, i.e., in-phase. The liquid jet is considered to be a penetrating jet. The jet is originated from the smaller bubble and clearly protruding outside of the bigger bubble. The parameter space of the relative size and the initiation distance of the bubble pair allowing the formation of the penetrating jet are very narrow. It is concluded that the liquid jet induced by the bubble interactions resulted from the collapse and the rebound of the smaller bubble nearby the bigger bubble. This is defined as the "catapult effect." Such a directional liquid transportation is a promising tool as a micro-injector or a micro-pump. The investigation results could be also supplementary to the understandings of the bubble dynamics.

Characterizing fluid dynamics in a bubble column aimed for the determination of reactive mass transfer

NASA Astrophysics Data System (ADS)

Kováts, Péter; Thévenin, Dominique; Zähringer, Katharina

2018-02-01

Bubble column reactors are multiphase reactors that are used in many process engineering applications. In these reactors a gas phase comes into contact with a fluid phase to initiate or support reactions. The transport process from the gas to the liquid phase is often the limiting factor. Characterizing this process is therefore essential for the optimization of multiphase reactors. For a better understanding of the transfer mechanisms and subsequent chemical reactions, a laboratory-scale bubble column reactor was investigated. First, to characterize the flow field in the reactor, two different methods have been applied. The shadowgraphy technique is used for the characterisation of the bubbles (bubble diameter, velocity, shape or position) for various process conditions. This technique is based on particle recognition with backlight illumination, combined with particle tracking velocimetry (PTV). The bubble trajectories in the column can also be obtained in this manner. Secondly, the liquid phase flow has been analysed by particle image velocimetry (PIV). The combination of both methods, delivering relevant information concerning disperse (bubbles) and continuous (liquid) phases, leads to a complete fluid dynamical characterization of the reactor, which is the pre-condition for the analysis of mass transfer between both phases.

An Euler-Lagrange method considering bubble radial dynamics for modeling sonochemical reactors.

PubMed

Jamshidi, Rashid; Brenner, Gunther

2014-01-01

Unsteady numerical computations are performed to investigate the flow field, wave propagation and the structure of bubbles in sonochemical reactors. The turbulent flow field is simulated using a two-equation Reynolds-Averaged Navier-Stokes (RANS) model. The distribution of the acoustic pressure is solved based on the Helmholtz equation using a finite volume method (FVM). The radial dynamics of a single bubble are considered by applying the Keller-Miksis equation to consider the compressibility of the liquid to the first order of acoustical Mach number. To investigate the structure of bubbles, a one-way coupling Euler-Lagrange approach is used to simulate the bulk medium and the bubbles as the dispersed phase. Drag, gravity, buoyancy, added mass, volume change and first Bjerknes forces are considered and their orders of magnitude are compared. To verify the implemented numerical algorithms, results for one- and two-dimensional simplified test cases are compared with analytical solutions. The results show good agreement with experimental results for the relationship between the acoustic pressure amplitude and the volume fraction of the bubbles. The two-dimensional axi-symmetric results are in good agreement with experimentally observed structure of bubbles close to sonotrode. Copyright © 2013 Elsevier B.V. All rights reserved.

Gender and gonadal maturity stage identification of captive Chinese sturgeon, Acipenser sinensis, using ultrasound imagery and sex steroids.

PubMed

Du, Hao; Zhang, Xiaoyan; Leng, Xiaoqian; Zhang, Shuhuan; Luo, Jiang; Liu, Zhigang; Qiao, Xingmei; Kynard, Boyd; Wei, Qiwei

2017-05-01

Long lifespan and late maturation make it difficult to establish gamete maturity and breeding age of captive endangered Chinese sturgeon, Acipenser sinensis. This greatly handicaps timely breeding and future conservation stocking efforts. We used ultrasound imagery and sex steroids to determine the gender and gonadal maturity stage of captive Chinese sturgeon (age, 10-17years old). The echogenicity of the reproductive organs and the respective morphology of the gonads were described and two quantitative parameters p o (proportion of the ovary to the entire reproductive organs) and d (thickness of the reproductive organs) were measured to characterize sex and maturity stage of Chinese sturgeon. Females were accordingly placed fish into several categories: F II (F II - , F II , F II + ), F III (F III , F III + ) and F IV (F IV , F IV + ) and F VI and males as M II , M III , M IV , M V and M VI . The accuracy of gender and maturity stage determination provided by ultrasonographic methods was 72.7% for F II - ovary (n=11) and 76.2% for M II testis (n=42). Accuracy of sex and maturity determination using only serum sex steroid of testosterone (T) and estradiol-17β (E 2 ) was low (58-73%, depending on maturity stage). However, when the two methods were used together, accuracy increased sharply, especially for immature (II stage) females. In summary, of 151 Chinese sturgeon, whose sex and maturity stage were independently confirmed, 88.1% (n=133), 62.9% (n=95), and 96.7% (n=146) were successfully sexed and staged using ultrasound, sex steroids, or both methods, respectively. The results provide reliable non-invasive techniques for determining sex and gonadal maturation of captive Chinese sturgeon. These methods can track individual gonad characteristics over multi-year reproductive cycles, which will assist captive broodstock management, artificial reproduction, and future conservation stocking. Copyright © 2016 Elsevier Inc. All rights reserved.

Far-Field Noise Induced by Bubble near Free Surface

NASA Astrophysics Data System (ADS)

Ye, Xi; Li, Jiang-tao; Liu, Jian-hua; Chen, Hai-long

2018-03-01

The motion of a bubble near the free surface is solved by the boundary element method based on the linear wave equation, and the influence of fluid compressibility on bubble dynamics is analyzed. Based on the solution of the bubble motion, the far-field radiation noise induced by the bubble is calculated using Kirchhoff moving boundary integral equation, and the influence of free surface on far-field noise is researched. As the results, the oscillation amplitude of the bubble is weakened in compressible fluid compared with that in incompressible fluid, and the free surface amplifies the effect of fluid compressibility. When the distance between the bubble and an observer is much larger than that between the bubble and free surface, the sharp wave trough of the sound pressure at the observer occurs. With the increment of the distance between the bubble and free surface, the time of the wave trough appearing is delayed and the value of the wave trough increase. When the distance between the observer and the bubble is reduced, the sharp wave trough at the observer disappears.

Investigation Into the Humaneness of Slaughter Methods for Guinea Pigs (Cavia porcelus) in the Andean Region

PubMed Central

Limon, Georgina; Gonzales-Gustavson, Eloy A.; Gibson, Troy J.

2016-01-01

Guinea pigs (Cavia porcelus) are an important source of nonhuman animal protein in the Andean region of South America. Specific guidelines regarding the welfare of guinea pigs before and during slaughter have yet to be developed. This study critically assessed the humaneness of 4 different stunning/slaughter methods for guinea pigs: cervical neck dislocation (n = 60), electrical head-only stunning (n = 83), carbon dioxide (CO2) stunning (n = 21), and penetrating captive bolt (n = 10). Following cervical neck dislocation, 97% of guinea pigs had at least 1 behavioral or cranial/spinal response. Six percent of guinea pigs were classified as mis-stunned after electrical stunning, and 1% were classified as mis-stunned after captive bolt. Increased respiratory effort was observed during CO2 stunning. Apart from this finding, there were no other obvious behavioral responses that could be associated with suffering. Of the methods assessed, captive bolt was deemed the most humane, effective, and practical method of stunning guinea pigs. Cervical neck dislocation should not be recommended as a slaughter method for guinea pigs. PMID:26963642

Path suppression of strongly collapsing bubbles at finite and low Reynolds numbers.

PubMed

Rechiman, Ludmila M; Dellavale, Damián; Bonetto, Fabián J

2013-06-01

We study, numerically and experimentally, three different methods to suppress the trajectories of strongly collapsing and sonoluminescent bubbles in a highly viscous sulfuric acid solution. A new numerical scheme based on the window method is proposed to account for the history force acting on a spherical bubble with variable radius. We could quantify the history force, which is not negligible in comparison with the primary Bjerknes force in this type of problem, and results are in agreement with the classical primary Bjerknes force trapping threshold analysis. Moreover, the present numerical implementation reproduces the spatial behavior associated with the positional and path instability of sonoluminescent argon bubbles in strongly gassed and highly degassed sulfuric acid solutions. Finally, the model allows us to demonstrate that spatially stationary bubbles driven by biharmonic excitation could be obtained with a different mode from the one used in previous reported experiments.

Numerical Modeling of Three-Dimensional Fluid Flow with Phase Change

NASA Technical Reports Server (NTRS)

Esmaeeli, Asghar; Arpaci, Vedat

1999-01-01

We present a numerical method to compute phase change dynamics of three-dimensional deformable bubbles. The full Navier-Stokes and energy equations are solved for both phases by a front tracking/finite difference technique. The fluid boundary is explicitly tracked by discrete points that are connected by triangular elements to form a front that is used to keep the stratification of material properties sharp and to calculate the interfacial source terms. Two simulations are presented to show robustness of the method in handling complex phase boundaries. In the first case, growth of a vapor bubble in zero gravity is studied where large volume increase of the bubble is managed by adaptively increasing the front resolution. In the second case, growth of a bubble under high gravity is studied where indentation at the rear of the bubble results in a region of large curvature which challenges the front tracking in three dimensions.

Dynamic film thickness between bubbles and wall in a narrow channel

NASA Astrophysics Data System (ADS)

Ito, Daisuke; Damsohn, Manuel; Prasser, Horst-Michael; Aritomi, Masanori

2011-09-01

The present paper describes a novel technique to characterize the behavior of the liquid film between gas bubbles and the wall in a narrow channel. The method is based on the electrical conductance. Two liquid film sensors are installed on both opposite walls in a narrow rectangular channel. The liquid film thickness underneath the gas bubbles is recorded by the first sensor, while the void fraction information is obtained by measuring the conductance between the pair of opposite sensors. Both measurements are taken on a large two-dimensional domain and with a high speed. This makes it possible to obtain the two-dimensional distribution of the dynamic liquid film between the bubbles and the wall. In this study, this method was applied to an air-water flow ranging from bubbly to churn regimes in the narrow channel with a gap width of 1.5 mm.

Numerical Study of Single Bubble Growth on and Departure from a Horizontal Superheated Wall by Three-dimensional Lattice Boltzmann Method

NASA Astrophysics Data System (ADS)

Feng, Yuan; Li, Hui-Xiong; Guo, Kai-Kai; Zhao, Jian-Fu; Wang, Tai

2018-05-01

A three-dimensional hybrid lattice Boltzmann method was used to simulate the progress of a single bubble's growth and departure from a horizontal superheated wall. The evolutionary process of the bubble shapes and also the temperature fields during pool nucleate boiling were obtained and the influence of the gravitational acceleration on the bubble departure diameter (BDD), the bubble release frequency (BRF) and the heat flux on the superheated wall was analyzed. The simulation results obtained by the present three-dimensional numerical studies demonstrate that the BDD is proportional to g^{-0.301}, the BRF is proportional to g^{-0.58}, and the averaged wall heat flux is proportional to g^{0.201}, where g is the gravitational acceleration. These results are in good agreement with the common-used experimental correlations, indicating the rationality of the present numerical model and results.

Cavitation inception by the backscattering of pressure waves from a bubble interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahira, Hiroyuki, E-mail: takahira@me.osakafu-u.ac.jp; Ogasawara, Toshiyuki, E-mail: oga@me.osakafu-u.ac.jp; Mori, Naoto, E-mail: su101064@edu.osakafu-u.ac.jp

2015-10-28

The secondary cavitation that occurs by the backscattering of focused ultrasound from a primary cavitation bubble caused by the negative pressure part of the ultrasound (Maxwell, et al., 2011) might be useful for the energy exchange due to bubble oscillations in High Intensity Focused Ultrasound (HIFU). The present study is concerned with the cavitation inception by the backscattering of ultrasound from a bubble. In the present experiment, a laser-induced bubble which is generated by a pulsed focused laser beam with high intensity is utilized as a primary cavitation bubble. After generating the bubble, focused ultrasound is emitted to the bubble.more » The acoustic field and the bubble motion are observed with a high-speed video camera. It is confirmed that the secondary cavitation bubble clouds are generated by the backscattering from the laser-induced bubble. The growth of cavitation bubble clouds is analyzed with the image processing method. The experimental results show that the height and width of the bubble clouds grow in stepwise during their evolution. The direct numerical simulations are also conducted for the backscattering of incident pressure waves from a bubble in order to evaluate a pressure field near the bubble. It is shown that the ratio of a bubble collapse time t{sub 0} to a characteristic time of wave propagation t{sub S}, η = t{sub 0}/t{sub s}, is an important determinant for generating negative pressure region by backscattering. The minimum pressure location by the backscattering in simulations is in good agreement with the experiment.« less

The tonic immobility test: Do wild and captive golden mantella frogs (Mantella aurantiaca) have the same response?

PubMed

Passos, Luiza Figueiredo; Garcia, Gerardo; Young, Robert John

2017-01-01

Adaptations to captivity that reduce fitness are one of many reasons, which explain the low success rate of reintroductions. One way of testing this hypothesis is to compare an important behavioural response in captive and wild members of the same species. Thanatosis, is an anti-predator strategy that reduces the risk of death from predation, which is a common behavioral response in frogs. The study subjects for this investigation were captive and wild populations of Mantella aurantiaca. Thanatosis reaction was measured using the Tonic Immobility (TI) test, a method that consists of placing a frog on its back, restraining it in this position for a short period of time and then releasing it and measuring how much time was spent feigning death. To understand the pattern of reaction time, morphometric data were also collected as body condition can affect the duration of thanatosis. The significantly different TI times found in this study, one captive population with shorter responses, were principally an effect of body condition rather than being a result of rearing environment. However, this does not mean that we can always dismiss the importance of rearing environment in terms of behavioural skills expressed.

Behavioral ecology of captive species: using behavioral adaptations to assess and enhance welfare of nonhuman zoo animals.

PubMed

Koene, Paul

2013-01-01

This project aimed to estimate a species' adaptations in nature and in captivity, assess welfare, suggest environmental changes, and find species characteristics that underlie welfare problems in nonhuman animals in the zoo. First, the current status of zoo animal welfare assessment was reviewed, and the behavioral ecology approach was outlined. In this approach, databases of species characteristics were developed using (a) literature of natural behavior and (b) captive behavior. Species characteristics were grouped in 8 functional behavioral ecological fitness-related categories: space, time, metabolic, safety, reproductive, comfort, social, and information adaptations. Assessments of the strength of behavioral adaptations in relation to environmental demands were made based on the results available from the literature. The databases with literature at the species level were coupled with databases of (c) behavioral observations and (d) welfare assessments under captive conditions. Observation and welfare assessment methods were adapted from the animal on the farm realm and applied to zoo species. It was expected that the comparison of the repertoire of behaviors in natural and captive environments would highlight welfare problems, provide solutions to welfare problems by environmental changes, and identify species characteristics underlying zoo animal welfare problems.

Breeding red-winged blackbirds in captivity

USGS Publications Warehouse

Know, C.J.; Stickley, A.R.

1974-01-01

Ability to establish and maintain self-sustaining breeding colonies of captive Red-winged Blackbirds (Agelaius phoeniceus) would facilitate long-term studies designed to develop methods for alleviating blackbird depredations as well as provide basic life history data. To be most useful, the colonies should be established in pens near laboratory facilities; this frequently involves putting colonies in unnatural nesting habitat. This paper describes a 5-year effort at Gainesville, Florida, to induce captive Red-wings, most of them taken from the wild as nestlings and then hand-reared in our laboratory, to breed regularly under such conditions. Except for an undocumented report of two young fully reared at the London Zoo in 1913 (Prestwick per. comm.), captive Red-wings have not been induced to breed successfully under avicultural conditions. In 1969, captive Red-wings, wild-trapped as adults, were induced to breed and to rear young successfully in large pens over normal marsh and hayfield nesting habitat in Ohio (Jackson pers. comm.). Earlier, a pair of Red-wings that had been caught as adults and kept together for a year hatched two young in a 40- X 20- X 6-foot cage in Massachusetts (Wetherbee 1960, Wilson Bull. 74: 90), but the nestlings died soon after hatching.

Degassing of molten alloys with the assistance of ultrasonic vibration

DOEpatents

Han, Qingyou; Xu, Hanbing; Meek, Thomas T.

2010-03-23

An apparatus and method are disclosed in which ultrasonic vibration is used to assist the degassing of molten metals or metal alloys thereby reducing gas content in the molten metals or alloys. High-intensity ultrasonic vibration is applied to a radiator that creates cavitation bubbles, induces acoustic streaming in the melt, and breaks up purge gas (e.g., argon or nitrogen) which is intentionally introduced in a small amount into the melt in order to collect the cavitation bubbles and to make the cavitation bubbles survive in the melt. The molten metal or alloy in one version of the invention is an aluminum alloy. The ultrasonic vibrations create cavitation bubbles and break up the large purge gas bubbles into small bubbles and disperse the bubbles in the molten metal or alloy more uniformly, resulting in a fast and clean degassing.

New impact sensitivity test of liquid explosives

NASA Astrophysics Data System (ADS)

Tiutiaev, Andrei; Trebunskih, Valeri

The sensitivity of liquid explosive in the presence of gas bubbles increases many times as compared with the liquid without gas bubbles. Local hot spot in this case formed as a result of compression and heating of the gas inside the bubbles. If we consider that in the liquid as a result of convection, wave motion, shock, etc. gas bubbles are easily generated, the need to develop a method for determining sensitivity of liquid explosives to impact and a detailed study of the ignition explosives with bubbles is obvious. On a mathematical model of a single steam bubbles in the fluid theoretically considered the process of initiating explosive liquid systems to impact. For the experimental investigation, the well-known K-44 -II with the metal cap were used. Instead of the metal cap in the standard method in this paper there was polyurethane foam cylindrical container with LHE, which is easily deforms by impact. A large number of tests with different liquid explosives were made. It was found that the test LHE to impact with polyurethane foam to a large extent reflect the real mechanical sensitivity due to the small loss of impact energy on the deformation of the metal cap, as well as the best differentiation LHE sensitivity due to the higher resolution method . Results obtained in the samara state technical university.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Shenyang; Setyawan, Wahyu; Joshi, Vineet V.

Xe gas bubble superlattice formation is observed in irradiated uranium–10 wt% molybdenum (U10Mo) fuels. However, the thermodynamic properties of the bubbles (the relationship among bubble size, equilibrium Xe concentration, and bubble pressure) and the mechanisms of bubble growth and superlattice formation are not well known. In this work, molecular dynamics is used to study these properties and mechanisms. The results provide important inputs for quantitative mesoscale models of gas bubble evolution and fuel performance. In the molecular dynamics simulations, the embedded-atom method (EAM) potential of U10Mo-Xe (Smirnova et al. 2013) is employed. Initial gas bubbles with low Xe concentration aremore » generated in a U10Mo single crystal. Then Xe atom atoms are continuously added into the bubbles, and the evolution of pressure and dislocation emission around the bubbles is analyzed. The relationship between pressure, equilibrium Xe concentration, and radius of the bubbles is established. It was found that the gas bubble growth is accompanied by partial dislocation emission, which results in a star-shaped dislocation structure and an anisotropic stress field. The emitted partial dislocations have a Burgers vector along the <111> direction and a slip plane of (11-2). Dislocation loop punch-out was not observed. A tensile stress was found along <110> directions around the bubble, favoring the nucleation and formation of a face-centered cubic bubble superlattice in body-centered cubic U10Mo fuels.« less

Imaging and analysis of individual cavitation microbubbles around dental ultrasonic scalers.

PubMed

Vyas, N; Dehghani, H; Sammons, R L; Wang, Q X; Leppinen, D M; Walmsley, A D

2017-11-01

Cavitation is a potentially effective and less damaging method of removing biofilm from biomaterial surfaces. The aim of this study is to characterise individual microbubbles around ultrasonic scaler tips using high speed imaging and image processing. This information will provide improved understanding on the disruption of dental biofilm and give insights into how the instruments can be optimised for ultrasonic cleaning. Individual cavitation microbubbles around ultrasonic scalers were analysed using high speed recordings up to a million frames per second with image processing of the bubble movement. The radius and rate of bubble growth together with the collapse was calculated by tracking multiple points on bubbles over time. The tracking method to determine bubble speed demonstrated good inter-rater reliability (intra class correlation coefficient: 0.993) and can therefore be a useful method to apply in future studies. The bubble speed increased over its oscillation cycle and a maximum of 27ms -1 was recorded during the collapse phase. The maximum bubble radii ranged from 40 to 80μm. Bubble growth was observed when the ultrasonic scaler tip receded from an area and similarly bubble collapse was observed when the tip moved towards an area, corresponding to locations of low pressure around the scaler tip. Previous work shows that this cavitation is involved in biofilm removal. Future experimental work can be based on these findings by using the protocols developed to experimentally analyse cavitation around various clinical instruments and comparing with theoretical calculations. This will help to determine the main cleaning mechanisms of cavitation and how clinical instruments such as ultrasonic scalers can be optimised. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

BUBBLE STRIPPING TO DETERMINE HYDROGEN CONCENTRATIONS IN GROUND WATER: A PRACTICAL APPLICATION OF HENRY'S LAW

EPA Science Inventory

The Bubble Stripping Method is a chemical testing method that operates on the principle of Henry's Law. It is useful for determining concentrations of hydrogen in well water, and it is capable of detecting concentrations on the order of nanomoles per liter. The method provides ...

Measurement and modeling on hydrodynamic forces and deformation of an air bubble approaching a solid sphere in liquids.

PubMed

Shahalami, Mansoureh; Wang, Louxiang; Wu, Chu; Masliyah, Jacob H; Xu, Zhenghe; Chan, Derek Y C

2015-03-01

The interaction between bubbles and solid surfaces is central to a broad range of industrial and biological processes. Various experimental techniques have been developed to measure the interactions of bubbles approaching solids in a liquid. A main challenge is to accurately and reliably control the relative motion over a wide range of hydrodynamic conditions and at the same time to determine the interaction forces, bubble-solid separation and bubble deformation. Existing experimental methods are able to focus only on one of the aspects of this problem, mostly for bubbles and particles with characteristic dimensions either below 100 μm or above 1 cm. As a result, either the interfacial deformations are measured directly with the forces being inferred from a model, or the forces are measured directly with the deformations to be deduced from the theory. The recently developed integrated thin film drainage apparatus (ITFDA) filled the gap of intermediate bubble/particle size ranges that are commonly encountered in mineral and oil recovery applications. Equipped with side-view digital cameras along with a bimorph cantilever as force sensor and speaker diaphragm as the driver for bubble to approach a solid sphere, the ITFDA has the capacity to measure simultaneously and independently the forces and interfacial deformations as a bubble approaches a solid sphere in a liquid. Coupled with the thin liquid film drainage modeling, the ITFDA measurement allows the critical role of surface tension, fluid viscosity and bubble approach speed in determining bubble deformation (profile) and hydrodynamic forces to be elucidated. Here we compare the available methods of studying bubble-solid interactions and demonstrate unique features and advantages of the ITFDA for measuring both forces and bubble deformations in systems of Reynolds numbers as high as 10. The consistency and accuracy of such measurement are tested against the well established Stokes-Reynolds-Young-Laplace model. The potential to use the design principles of the ITFDA for fundamental and developmental research is demonstrated. Copyright © 2014. Published by Elsevier B.V.

Bubble velocity, diameter, and void fraction measurements in a multiphase flow using fiber optic reflectometer

NASA Astrophysics Data System (ADS)

Lim, Ho-Joon; Chang, Kuang-An; Su, Chin B.; Chen, Chi-Yueh

2008-12-01

A fiber optic reflectometer (FOR) technique featuring a single fiber probe is investigated for its feasibility of measuring the bubble velocity, diameter, and void fraction in a multiphase flow. The method is based on the interference of the scattered signal from the bubble surface with the Fresnel reflection signal from the tip of the optical fiber. Void fraction is obtained with a high accuracy if an appropriate correction is applied to compensate the underestimated measurement value. Velocity information is accurately obtained from the reflected signals before the fiber tip touches the bubble surface so that several factors affecting the traditional dual-tip probes such as blinding, crawling, and drifting effects due to the interaction between the probe and bubbles can be prevented. The coherent signals reflected from both the front and rear ends of a bubble can provide velocity information. Deceleration of rising bubbles and particles due to the presence of the fiber probe is observed when they are very close to the fiber tip. With the residence time obtained, the bubble chord length can be determined by analyzing the coherent signal for velocity determination before the deceleration starts. The bubble diameters are directly obtained from analyzing the signals of the bubbles that contain velocity information. The chord lengths of these bubbles measured by FOR represent the bubble diameters when the bubble shape is spherical or represent the minor axes when the bubble shape is ellipsoidal. The velocity and size of bubbles obtained from the FOR measurements are compared with those obtained simultaneously using a high speed camera.

Conservation Genetics of Threatened Hippocampus guttulatus in Vulnerable Habitats in NW Spain: Temporal and Spatial Stability of Wild Populations with Flexible Polygamous Mating System in Captivity

PubMed Central

López, Almudena; Vera, Manuel; Planas, Miquel; Bouza, Carmen

2015-01-01

This study was focused on conservation genetics of threatened Hippocampus guttulatus on the Atlantic coast of NW Iberian Peninsula. Information about spatial structure and temporal stability of wild populations was obtained based on microsatellite markers, and used for monitoring a captive breeding program firstly initiated in this zone at the facilities of the Institute of Marine Research (Vigo, Spain). No significant major genetic structure was observed regarding the biogeographical barrier of Cape Finisterre. However, two management units under continuous gene flow are proposed based on the allelic differentiation between South-Atlantic and Cantabrian subpopulations, with small to moderate contemporary effective size based on single-sample methods. Temporal stability was observed in South-Atlantic population samples of H. guttulatus for the six-year period studied, suggesting large enough effective population size to buffer the effects of genetic drift within the time frame of three generations. Genetic analysis of wild breeders and offspring in captivity since 2009 allowed us to monitor the breeding program founded in 2006 in NW Spain for this species. Similar genetic diversity in the renewed and founder broodstock, regarding the wild population of origin, supports suitable renewal and rearing processes to maintain genetic variation in captivity. Genetic parentage proved single-brood monogamy in the wild and in captivity, but flexible short- and long-term mating system under captive conditions, from strict monogamy to polygamy within and/or among breeding seasons. Family analysis showed high reproductive success in captivity under genetic management assisted by molecular relatedness estimates to avoid inbreeding. This study provides genetic information about H. guttulatus in the wild and captivity within an uncovered geographical range for this data deficient species, to be taken into account for management and conservation purposes. PMID:25646777

Bubble Transport through Micropillar Arrays

NASA Astrophysics Data System (ADS)

Lee, Kenneth; Savas, Omer

2012-11-01

In current energy research, artificial photosynthetic devices are being designed to split water and harvest hydrogen gas using energy from the sun. In one such design, hydrogen gas bubbles evolve on the catalytic surfaces of arrayed micropillars. If these bubbles are not promptly removed from the surface, they can adversely affect gas evolution rates, water flow rates, sunlight capture, and heat management of the system. Therefore, an efficient method of collecting the evolved gas bubbles is crucial. Preliminary flow visualization has been conducted of bubbles advecting through dense arrays of pillars. Bubbles moving through square and hexagonal arrays are tracked, and the results are qualitatively described. Initial attempts to correlate bubble motion with relevant lengthscales and forces are also presented. These observations suggest how bubble transport within such pillar arrays can be managed, as well as guide subsequent experiments that investigate bubble evolution and collection. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.

Numerical investigation of bubble nonlinear dynamics characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Jie, E-mail: shijie@hrbeu.edu.cn; Yang, Desen; Shi, Shengguo

2015-10-28

The complicated dynamical behaviors of bubble oscillation driven by acoustic wave can provide favorable conditions for many engineering applications. On the basis of Keller-Miksis model, the influences of control parameters, including acoustic frequency, acoustic pressure and radius of gas bubble, are discussed by utilizing various numerical analysis methods, Furthermore, the law of power spectral variation is studied. It is shown that the complicated dynamic behaviors of bubble oscillation driven by acoustic wave, such as bifurcation and chaos, further the stimulated scattering processes are revealed.

Oceanic Gas Bubble Measurements Using an Acoustic Bubble Spectrometer

NASA Astrophysics Data System (ADS)

Wilson, S. J.; Baschek, B.; Deane, G.

2008-12-01

Gas bubble injection by breaking waves contributes significantly to the exchange of gases between atmosphere and ocean at high wind speeds. In this respect, CO2 is primarily important for the global ocean and climate, while O2 is especially relevant for ecosystems in the coastal ocean. For measuring oceanic gas bubble size distributions, a commercially available Dynaflow Acoustic Bubble Spectrometer (ABS) has been modified. Two hydrophones transmit and receive selected frequencies, measuring attenuation and absorption. Algorithms are then used to derive bubble size distributions. Tank test were carried out in order to test the instrument performance.The software algorithms were compared with Commander and Prosperetti's method (1989) of calculating sound speed ratio and attenuation for a known bubble distribution. Additional comparisons with micro-photography were carried out in the lab and will be continued during the SPACE '08 experiment in October 2008 at Martha's Vineyard Coastal Observatory. The measurements of gas bubbles will be compared to additional parameters, such as wind speed, wave height, white cap coverage, or dissolved gases.

Stability of cavitation structures in a thin liquid layer.

PubMed

Wu, Pengfei; Bai, Lixin; Lin, Weijun; Yan, Jiuchun

2017-09-01

The inception and evolution of acoustic cavitation structures in thin liquid layers under different conditions and perturbations are investigated experimentally with high speed photography. The stability and characterization of cavitation structures are quantified by image analysis methods. It is found that cavitation structures (shape of bubble cloud and number of bubbles) are stable under unaltered experimental conditions, and the cavitation bubble cloud will return to the original structure and remain stable even in the face of large perturbations. When the experimental conditions are altered (for example, acoustic intensity, cavitation nuclei, boundary), the cavitation structures will vary correspondingly. Further analysis implies that the stability of cavitation structures is closely related to the number of bubbles in the cavitation bubble cloud. There are two mechanisms acting simultaneously in the cavitation bubble cloud evolution, one "bubble production" and the other "bubble disappearance". We propose that the two mechanisms acting together constitute the most likely explanation for the stability of cavitation structures and their transformation. Copyright © 2017 Elsevier B.V. All rights reserved.

Spatial-temporal ultrasound imaging of residual cavitation bubbles around a fluid-tissue interface in histotripsy.

PubMed

Hu, Hong; Xu, Shanshan; Yuan, Yuan; Liu, Runna; Wang, Supin; Wan, Mingxi

2015-05-01

Cavitation is considered as the primary mechanism of soft tissue fragmentation (histotripsy) by pulsed high-intensity focused ultrasound. The residual cavitation bubbles have a dual influence on the histotripsy pulses: these serve as nuclei for easy generation of new cavitation, and act as strong scatterers causing energy "shadowing." To monitor the residual cavitation bubbles in histotripsy, an ultrafast active cavitation imaging method with relatively high signal-to-noise ratio and good spatial-temporal resolution was proposed in this paper, which combined plane wave transmission, minimum variance beamforming, and coherence factor weighting. The spatial-temporal evolutions of residual cavitation bubbles around a fluid-tissue interface in histotripsy under pulse duration (PD) of 10-40 μs and pulse repetition frequency (PRF) of 0.67-2 kHz were monitored by this method. The integrated bubble area curves inside the tissue interface were acquired from the bubble image sequence, and the formation process of histotripsy damage was estimated. It was observed that the histotripsy efficiency decreased with both longer PDs and higher PRFs. A direct relationship with a coefficient of 1.0365 between histotripsy lesion area and inner residual bubble area was found. These results can assist in monitoring and optimization of the histotripsy treatment further.

Urinary corticosterone metabolite responses to capture and captivity in the cane toad (Rhinella marina).

PubMed

Narayan, Edward J; Cockrem, John F; Hero, Jean-Marc

2011-09-01

Urinary corticosterone metabolite responses to capture have recently been shown for the first time in amphibians, and in the present study urinary corticosterone metabolite responses to capture and to confinement in captivity were measured in adult cane toads (Rhinella marina) in Queensland, Australia. An adrenocorticotropic hormone (ACTH) challenge was used to provide a biological validation for urinary corticosterone metabolite concentrations measured by radioimmunoassay (RIA). Urinary corticosterone metabolite increased 1-2 days after ACTH but not saline injection and then returned to initial values, indicating that the RIA could detect changes in corticosterone secretion in toads. Urinary corticosterone metabolite responses to short-term capture and restraint in plastic bags were first apparent 2h after capture of wild toads. Toads held communally in captivity for 5 days had elevated urinary corticosterone metabolite concentrations. Mean corticosterone concentrations declined significantly after a further 7 days in individual housing chambers. There was no sex difference in urinary corticosterone metabolite responses of toads to ACTH challenge, short-term capture or captivity. The relative amount of variation in the mean corticosterone responses was quantified by calculating coefficients of variation (CV) for each mean corticosterone response. Mean corticosterone at 0 min was more variable for captive toads than wild toads. Furthermore, initial corticosterone concentrations (0 min) were more variable than concentrations during the ACTH challenge, short-term capture and captivity. There was little change in the amount of variation of mean corticosterone levels between male and female toads with increasing time in captivity (12-29 days). This study has shown individual corticosterone responses of amphibians for the first-time, and has provided a novel method for quantifying the relative amount of variation in amphibian corticosterone responses. Copyright © 2011 Elsevier Inc. All rights reserved.

Thyroxine-induced metamorphosis in the axolotl (Ambystoma mexicanum).

PubMed

Coots, Peggy S; Seifert, Ashley W

2015-01-01

The axolotl (Ambystoma mexicanum) has remained an important model for regeneration and developmental biology for over a century. Although axolotls in captive-bred colonies usually exist in an aquatic form, they retain the ability to undergo metamorphosis following exposure to thyroid hormone. Here we present a robust method for inducing metamorphosis in adult axolotls that results in high survivability and produces terrestrial animals that can be maintained in long-term captivity.

Behavioral responses of three lemur species to different food enrichment devices.

PubMed

Shapiro, Morgan E; Shapiro, Hannah G; Ehmke, Erin E

2018-05-01

Environmental enrichment is a tool used to promote the welfare and well-being of captive animals by encouraging the display of species-specific behaviors and reducing the stress or boredom induced by captive environments. Lemurs are highly endangered, yet few studies have analyzed the behavioral impacts of enrichment on captive populations. We studied the impacts of two novel enrichment devices on three lemur species (ring-tailed lemurs [Lemur catta], red-ruffed lemurs [Varecia rubra], and Coquerel's sifaka [Propithecus coquereli]) to determine both the overall and species-specific impacts of enrichment on lemur behavior. We recorded lemur behavior using the continuous sampling method to obtain behavior duration and analyzed our results using ANOVA Repeated Measures. Results showed enrichment effectiveness differed for each species and that different enrichment devices had varying impacts on lemur behavior across all species. We attributed the differences in species-specific responses to the unique locomotor patterns and methods of diet acquisition of each species, and the variances in behavioral responses across all species to the characteristics of each device. Our study highlights the importance of species-specific enrichment and encourages further research in this field in order to maximize the positive effects of enrichment, which in turn has the potential to affect the overall well-being of captive populations. © 2018 Wiley Periodicals, Inc.

Basal body temperature method for detecting ovarian cycle in the Captive Beluga (Delphinapterus leucas).

PubMed

Katsumata, Etsuko; Furuta, Chie; Katsumata, Hiroshi; Watanabe, Gen; Taya, Kazuyoshi

2006-02-01

The relationship between basal body temperature and circulating progesterone levels were investigated in a female beluga. Body temperature and serum concentrations of progesterone were measured daily and at 2-4 week intervals respectively, in a female beluga that was in captivity for 7 years between 1996 and 2003. The beluga first ovulated in April, 2000 (13 years old). Thereafter, serum concentrations of progesterone showed cyclic changes, indicating that the ovulatory cycle had started. Serum concentrations of progesterone ranged from 0.1 ng/ml to 15.7 ng/ml. Body temperature also showed cyclic changes during the estrous cycle. Body temperature ranged from 34.9 to 35.9 C, and tended to reach the peak during the high progesterone phase. Mating behavior was observed during the low body temperature phase. The changes in body temperature positively correlated with the circulating progesterone levels. The length of the estrous cycle was 36.7 +/- 3.9 (mean +/- SEM) days based on the intervals between the days of mating behavior. This is the first report demonstrating that body temperature clearly changes during the estrous cycle in a captive female beluga. The present finding suggests that measurement of body temperature is a useful method for detecting the ovarian cycle of the beluga in captivity.

THE BUBBLE STRIPPING METHOD FOR DETERMINING DISSOLVED HYDROGEN (H2) IN WELL WATER

EPA Science Inventory

The Bubble Strip Method was developed for determining concentrations of dissolved H2 in ground water (1). This information canaid in assessing the viability of employing the strategyof monitored natural attenuation (MNA) to restore sites contaminated with chlorinated hydrocarbon...

Evaluation of methods for the euthanasia of cattle in a foreign animal disease outbreak.

PubMed Central

Baker, H J; Scrimgeour, H J

1995-01-01

In anticipation of the need to euthanize large numbers of cattle in the event of a foreign animal disease outbreak, two models of captive bolt gun and various firearms and ammunition loads were tested in order to assess their suitability. In the first phase of the project, two models of captive bolt stunner were used in an abattoir, and assessed for effectiveness. In the second phase, several firearms and ammunition were used on isolated bovine heads and assessed for effectiveness. Little difference was found between the two captive bolt stunners. Of the firearms and ammunition evaluated, the Ruger Mini-14 and the Core-Shot round, a prefragmented projectile, were determined to be most suitable. In situations where large herds of livestock are to be depopulated, and where the restraint required for the use of captive bolt stunners is not practical, there are commercially available firearms and ammunition that are suitable for this purpose. PMID:7757921

Formation of soap bubbles by gas jet

NASA Astrophysics Data System (ADS)

Zhou, Maolei; Li, Min; Chen, Zhiyuan; Han, Jifeng; Liu, Dong

2017-12-01

Soap bubbles can be easily generated by various methods, while their formation process is complicated and still worth studying. A model about the bubble formation process was proposed in the study by Salkin et al. [Phys. Rev. Lett. 116, 077801 (2016)] recently, and it was reported that the bubbles were formed when the gas blowing velocity was above one threshold. However, after a detailed study of these experiments, we found that the bubbles could be generated in two velocity ranges which corresponded to the laminar and turbulent gas jet, respectively, and the predicted threshold was only effective for turbulent gas flow. The study revealed that the bubble formation was greatly influenced by the aerodynamics of the gas jet blowing to the film, and these results will help to further understand the formation mechanism of the soap bubble as well as the interaction between the gas jet and the thin liquid film.

Characterisation of gene delivery using liposomal bubbles and ultrasound

NASA Astrophysics Data System (ADS)

Koshima, Risa; Suzuki, Ryo; Oda, Yusuke; Hirata, Keiichi; Nomura, Tetsuya; Negishi, Yoichi; Utoguchi, Naoki; Kudo, Nobuki; Maruyama, Kazuo

2011-09-01

The combination of nano/microbubbles and ultrasound is a novel technique for a non-viral gene deliver. We have previously developed novel ultrasound sensitive liposomes (Bubble liposomes) which contain the ultrasound imaging gas perfluoropropane. In this study, Bubble liposomes were compared with cationic lipid (CL)-DNA complexes as potential gene delivery carriers into tumors in vivo. The delivery of genes by bubble liposomes depended on the intensity of the applied ultrasound. The transfection efficiency plateaued at 0.7 W/cm2 ultrasound intensity. Bubble liposomes efficiently transferred genes into cultured cells even when the cells were exposed to ultrasound for only 1 s. In addition, bubble liposomes were able to introduce the luciferase gene more effectively than CL-DNA complexes into mouse ascites tumor cells. We conclude that the combination of Bubble liposomes and ultrasound is a good method for gene transfer in vivo.

A Portable Ecosystem.

ERIC Educational Resources Information Center

Abell, Sandra K.

1988-01-01

Introduces a construction method for a bubble made of polyurethane plastic and its applications in an ecology classroom. Provides the materials list, directions for bubble construction, and classroom activities. (YP)

Effect of captivity on morphology: negligible changes in external morphology mask significant changes in internal morphology

PubMed Central

Munn, Adam J.; Byrne, Phillip G.

2018-01-01

Captive breeding programmes are increasingly relied upon for threatened species management. Changes in morphology can occur in captivity, often with unknown consequences for reintroductions. Few studies have examined the morphological changes that occur in captive animals compared with wild animals. Further, the effect of multiple generations being maintained in captivity, and the potential effects of captivity on sexual dimorphism remain poorly understood. We compared external and internal morphology of captive and wild animals using house mouse (Mus musculus) as a model species. In addition, we looked at morphology across two captive generations, and compared morphology between sexes. We found no statistically significant differences in external morphology, but after one generation in captivity there was evidence for a shift in the internal morphology of captive-reared mice; captive-reared mice (two generations bred) had lighter combined kidney and spleen masses compared with wild-caught mice. Sexual dimorphism was maintained in captivity. Our findings demonstrate that captive breeding can alter internal morphology. Given that these morphological changes may impact organismal functioning and viability following release, further investigation is warranted. If the morphological change is shown to be maladaptive, these changes would have significant implications for captive-source populations that are used for reintroduction, including reduced survivorship.

Effect of ultrasound on dynamics characteristic of the cavitation bubble in grinding fluids during honing process.

PubMed

Guo, Ce; Zhu, Xijing

2018-03-01

The effect of ultrasound on generating and controlling the cavitation bubble of the grinding fluid during ultrasonic vibration honing was investigated. The grinding fluid on the surface of the honing stone was measured by utilizing the digital microscope VHX-600ESO. Based on analyzing the cavitation mechanism of the grinding fluid, the bubble dynamics model under conventional honing (CH) and ultrasonic vibration honing (UVH) was established respectively. Difference of dynamic behaviors of the bubble between the cases in UVH and CH was compared respectively, and the effects of acoustic amplitude and ultrasonic frequency on the bubble dynamics were simulated numerically using the Runge-Kutta fourth order method with variable step size adaptive control. Finally, the cavitation intensity of grinding fluids under ultrasound was measured quantitatively using acoustimeter. The results showed that the grinding fluid subjected to ultrasound can generate many bubbles and further forms numerous groups of araneose cavitation bubbles on the surface of the honing stone. The oscillation of the bubble under UVH is more intense than the case under CH, and the maximum velocity of the bubble wall under UVH is higher two magnitudes than the case under CH. For lower acoustic amplitude, the dynamic behaviors of the bubble under UVH are similar to that case under CH. As increasing acoustic amplitude, the cavitation intensity of the bubble is growing increased. Honing pressure has an inhabitation effect on cavitation effect of the grinding fluid. The perfect performance of cavitation of the grinding fluid can be obtained when the device of UVH is in the resonance. However, the cavitation intensity of the grinding fluid can be growing weakened with increasing ultrasonic frequency, when the device of UVH is in the off-resonance. The experimental results agree with the theoretical and numerical analysis, which provides a method for exploring applications of the cavitation effect in ultrasonic assisted machining. Copyright © 2017 Elsevier B.V. All rights reserved.

Donald Glaser, the Bubble Chamber, and Elementary Particles

Science.gov Websites

Effects of Ionizing Radiation on the Formation of Bubbles in Liquids Physical Review, Vol. 87, Issue 4 , 665, August 15, 1952 Characteristics of Bubble Chambers Physical Review, Vol. 97, Issue 2, 474-479 Chambers Physical Review, Vol. 102, Issue 6, 1653-1658, June 15, 1956 Methods of Particle Detection for

Simulation of gas bubbles in hypobaric decompressions: roles of O2, CO2, and H2O.

PubMed

Van Liew, H D; Burkard, M E

1995-01-01

To gain insight into the special features of bubbles that may form in aviators and astronauts, we simulated the growth and decay of bubbles in two hypobaric decompressions and a hyperbaric one, all with the same tissue ratio (TR), where TR is defined as tissue PN2 before decompression divided by barometric pressure after. We used an equation system which is solved by numerical methods and accounts for simultaneous diffusion of any number of gases as well as other major determinants of bubble growth and absorption. We also considered two extremes of the number of bubbles which form per unit of tissue. A) Because physiological mechanisms keep the partial pressures of the "metabolic" gases (O2, CO2, and H2O) nearly constant over a range of hypobaric pressures, their fractions in bubbles are inversely proportional to pressure and their large volumes at low pressure add to bubble size. B) In addition, the large fractions facilitate the entry of N2 into bubbles, and when bubble density is low, enhance an autocatalytic feedback on bubble growth due to increasing surface area. C) The TR is not closely related to bubble size; that is when two different decompressions have the same TR, metabolic gases cause bubbles to grow larger at lower hypobaric pressures. We conclude that the constancy of partial pressures of metabolic gases, unimportant in hyperbaric decompressions, affects bubble size in hypobaric decompressions in inverse relation to the exposure pressure.

Fabricated nanogap-rich plasmonic nanostructures through an optothermal surface bubble in a droplet.

PubMed

Karim, Farzia; Vasquez, Erick S; Zhao, Chenglong

2018-01-15

A rapid and cost-effective method for the fabrication of nanogap-rich structures is demonstrated in this Letter. The method utilizes the Marangoni convection around an optothermal surface bubble inside a liquid droplet with a nanoliter volume. The liquid droplet containing metallic nanoparticles reduces the sample consumption and confines the liquid flow. The optothermal surface bubble creates a strong convective flow that allows for the rapid deposition of the metallic nanoparticles to form nanogap-rich structures on any substrate under ambient conditions. This method will enable a broad range of applications such as biosensing, environmental analysis, and nonlinear optics.

Perturbation of a radially oscillating single-bubble by a micron-sized object.

PubMed

Montes-Quiroz, W; Baillon, F; Louisnard, O; Boyer, B; Espitalier, F

2017-03-01

A single bubble oscillating in a levitation cell is acoustically monitored by a piezo-ceramics microphone glued on the cell external wall. The correlation of the filtered signal recorded over distant cycles on one hand, and its harmonic content on the other hand, are shown to carry rich information on the bubble stability and existence. For example, the harmonic content of the signal is shown to increase drastically once air is fully dissociated in the bubble, and the resulting pure argon bubble enters into the upper branch of the sonoluminescence regime. As a consequence, the bubble disappearance can be unambiguously detected by a net drop in the harmonic content. On the other hand, we perturb a stable sonoluminescing bubble by approaching a micron-sized fiber. The bubble remains unperturbed until the fiber tip is approached within a critical distance, below which the bubble becomes unstable and disappears. This distance can be easily measured by image treatment, and is shown to scale roughly with 3-4 times the bubble maximal radius. The bubble disappearance is well detected by the drop of the microphone harmonic content, but several thousands of periods after the bubble actually disappeared. The delay is attributed to the slow extinction of higher modes of the levitation cell, excited by the bubble oscillation. The acoustic detection method should however allow the early detection and imaging of non-predictable perturbations of the bubble by foreign micron-sized objects, such as crystals or droplets. Copyright © 2016 Elsevier B.V. All rights reserved.

Numerical Analysis of the Influence of Low Frequency Vibration on Bubble Growth

PubMed Central

Han, D.; Kedzierski, Mark A.

2017-01-01

Numerical simulation of bubble growth during pool boiling under the influence of low frequency vibration was performed to understand the influence of common vibrations such as those induced by wind, highway transportation, and nearby mechanical devices on the performance of thermal systems that rely on boiling. The simulations were done for saturated R123 boiling at 277.6 K with a 15 K wall superheat. The numerical volume-of-fluid method (fixed grid) was used to define the liquid-vapor interface. The basic bubble growth characteristics including the bubble departure diameter and the bubble departure time were determined as a function of the bubble contact angle (20°–80°), the vibration displacement (10 µm–50 µm), the vibration frequency (5 Hz–25 Hz), and the initial vibration direction (positive or negative). The bubble parameters were shown to be strongly dependent on the bubble contact angle at the surface. For example, both the bubble departure diameter and the bubble departure time increased with the contact angle. At the same vibration frequency and the initial vibration direction, the bubble departure diameter and the bubble departure time both decreased with increasing vibration displacement. In addition, the vibration frequency had a greater effect on the bubble growth characteristics than did the vibration displacement. The vibration frequency effect was strongly influenced by the initial vibration direction. The pressure contour, the volume fraction of vapor phase, the temperature profile, and the velocity vector were investigated to understand these dynamic bubble behaviors. The limitation of the computational fluid dynamics approach was also described. PMID:28747812

Molecular screening for hemotropic mycoplasmas in captive Barbary sheep (Ammotragus lervia) in southern Brazil

PubMed Central

Santos, Leonilda C.; Vidotto, Odilon; Morikawa, Vivien M.; Santos, Nelson J. R.; Vieira, Thállitha S. W. J.; Barros Filho, Ivan R.; Vieira, Rafael F. C.; Biondo, Alexander W.

2017-01-01

Aim: This study is part of an active surveillance program for monitoring animal health status in endangered species, and was conducted to screen captive Barbary sheep (Ammotragus lervia) for hemoplasma infection. Materials and Methods: A total of 12 blood samples were collected, DNA extracted and further tested by a pan-hemoplasma polymerase chain reaction protocol. Results: Animals were clinically healthy and not infested by ectoparasites. Although housekeeping gene DNA was successfully amplified, all the Barbary sheep samples tested negative for Mycoplasma sp. Conclusion: Notwithstanding the negative results, molecular pathogen surveys on Barbary sheep and other exotic wild mammals may provide insights regarding infection of endangered species caused by captivity stress in association with exposure to new pathogens worldwide. PMID:28919684

Lab-on-a-bubble: direct and indirect assays with portable Raman instrumentation

NASA Astrophysics Data System (ADS)

Carron, Keith; Schmit, Virginia; Scott, Brandon; Martoglio, Richard

2012-10-01

Lab-on-a-Bubble (LoB) is a new method for SERS (Surface Enhanced Raman Scattering) assays that combines separationand concentration of the assay results. A direct LoB assay is comprised of gold nanoparticles coupled directly to the ~30 μm diameter buoyant silica bubble. The direct LoB method was evaluated with cyanide and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). An indirect assay uses the same ~ 30 μm diameter buoyant silica bubble and a silica coated SERS reporter. Both the bubble and SERS reporter are coated with a coupling agent for the analyte. The assay measures the amount of SERS reporter coupled to the bubble through a sandwich created by the analyte. The couling agent could consist of an immunological coupling agent (antibody) or a nucleic acid coupling agent (single strand DNA). The indirect LoB method was examined with Cholera toxin (CT) and antibodies against the β subunit. An LOD of ~ 170 pptrillion was measured for cyanide and a limit of detection of 1100 ng was found for CT. Instrumentation for the assay and a novel technique of dynamic SERS (DSERS) will also be discussed. The instrument is a small hand-held Raman device called the CBEx (Chemical Biological Explosive) with a novel raster system to detect heterogeneous or light sensitive materials. DSERS is a mathematical algorithm which eliminates background interference in SERS measurements with colloidal nanoparticles.

Numerical modeling of Stokes flows over a superhydrophobic surface containing gas bubbles

NASA Astrophysics Data System (ADS)

Ageev, A. I.; Golubkina, I. V.; Osiptsov, A. N.

2017-10-01

This paper continues the numerical modeling of Stokes flows near cavities of a superhydrophobic surface, occupied by gas bubbles, based on the Boundary Element Method (BEM). The aim of the present study is to estimate the friction reduction (pressure drop) in a microchannel with a bottom superhydrophobic surface, the texture of which is formed by a periodic system of striped rectangular microcavities containing compressible gas bubbles. The model proposed takes into account the streamwise variation of the bubble shift into the cavities, caused by the longitudinal pressure gradient in the channel flow. The solution for the macroscopic (averaged) flow in the microchannel, constructed using an effective slip boundary condition on the superhydrophobic bottom wall, is matched with the solution of the Stokes problem at the microscale of a single cavity containing a gas bubble. The 2D Stokes problems of fluid flow over single cavities containing curved phase interfaces with the condition of zero shear stress are reduced to the boundary integral equations which are solved using the BEM method.

A mimetic finite difference method for the Stokes problem with elected edge bubbles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipnikov, K; Berirao, L

2009-01-01

A new mimetic finite difference method for the Stokes problem is proposed and analyzed. The unstable P{sub 1}-P{sub 0} discretization is stabilized by adding a small number of bubble functions to selected mesh edges. A simple strategy for selecting such edges is proposed and verified with numerical experiments. The discretizations schemes for Stokes and Navier-Stokes equations must satisfy the celebrated inf-sup (or the LBB) stability condition. The stability condition implies a balance between discrete spaces for velocity and pressure. In finite elements, this balance is frequently achieved by adding bubble functions to the velocity space. The goal of this articlemore » is to show that the stabilizing edge bubble functions can be added only to a small set of mesh edges. This results in a smaller algebraic system and potentially in a faster calculations. We employ the mimetic finite difference (MFD) discretization technique that works for general polyhedral meshes and can accomodate non-uniform distribution of stabilizing bubbles.« less

Species differences in hematological values of captive cranes, geese, raptors, and quail

USGS Publications Warehouse

Gee, G.F.; Carpenter, J.W.; Hensler, G.L.

1981-01-01

Hematological and serum chemical constituents of blood were determined for 12 species, including 7 endangered species, of cranes, geese, raptors, and quail in captivity at the Patuxent Wildlife Research Center. Means, standard deviations, analysis of variance by species and sex, and a series of multiple comparisons of means were derived for each parameter investigated. Differences among some species means were observed in all blood parameters except gamma-glutamyl transpeptidase. Although sampled during the reproductively quiescent period, an influence of sex was noted in red blood cell count, hemoglobin, albumin, glucose, cholesterol, serum glutamic oxaloacetic transaminase, Ca, and P. Our data and values reported in literature indicate that most hematological parameters vary among species and, in some cases, according to methods used to determine them. Therefore, baseline data for captive and wild birds should be established by using standard methods, and should be made available to aid others for use in assessing physiological and pathological conditions of these species.

Hematological markers and biochemical profiles in terms of gender and age of captive collared peccaries (Tayassu tajacu) in eastern Amazon.

PubMed

Jorge, E M; Silva, C J O; Ritter, R A; Monteiro, M V B; Albuquerque, N I; Kahwage, P R; Monteiro, F O B; Costa, C T C; Rahal, S C; Silva Filho, E

2015-11-25

Complete blood counts and blood biochemical analyses are laboratory tests that allow the monitoring of physiological condition, nutrition, and health in free-living or captive wild animals. When interpreting these tests, it is essential to compare the results with reference ranges that are suitable for the species. Few studies have been conducted on the hematological and biochemical characteristics of Tayassu tajacu, particularly for animals raised in the Amazon biome. The objectives of this study were to evaluate the influence of age and gender on the hematological and biochemical profiles of captive T. tajacu, and to establish reference intervals for these parameters. Complete blood counts and biochemical analyses were performed using manual methods and semi-automatic equipment, respectively. There were significant differences in relation to age in hematocrit and hemoglobin levels, and mean cell volumes, in captive T. tajacu. No basophils were observed, and the neutrophil:lymphocyte ratio was less than 1. Levels of total protein, urea, phosphorus, and alkaline phosphatase were significantly affected by age (P < 0.05). Gender did not affect any of the results. The hematological and biochemical parameters for this species were determined, and may be used as reference ranges for captive T. tajacu.

Noise analysis of nucleate boiling

NASA Technical Reports Server (NTRS)

Mcknight, R. D.; Ram, K. S.

1971-01-01

The techniques of noise analysis have been utilized to investigate nucleate pool boiling. A simple experimental setup has been developed for obtaining the power spectrum of a nucleate boiling system. These techniques were first used to study single bubbles, and a method of relating the two-dimensional projected size and the local velocity of the bubbles to the auto-correlation functions is presented. This method is much less time consuming than conventional methods of measurement and has no probes to disturb the system. These techniques can be used to determine the contribution of evaporation to total heat flux in nucleate boiling. Also, these techniques can be used to investigate the effect of various parameters upon the frequency response of nucleate boiling. The predominant frequencies of the power spectrum correspond to the frequencies of bubble generation. The effects of heat input, degree of subcooling, and liquid surface tension upon the power spectra of a boiling system are presented. It was found that the degree of subcooling has a more pronounced effect upon bubble size than does heat flux. Also the effect of lowering surface tension can be sufficient to reduce the effect of the degree of subcooling upon the size of the bubbles.

Generation of Microbubbles with Applications to Industry and Medicine

NASA Astrophysics Data System (ADS)

Rodríguez-Rodríguez, Javier; Sevilla, Alejandro; Martínez-Bazán, Carlos; Gordillo, José Manuel

2015-01-01

We provide a comprehensive and systematic description of the diverse microbubble generation methods recently developed to satisfy emerging technological, pharmaceutical, and medical demands. We first introduce a theoretical framework unifying the physics of bubble formation in the wide variety of existing types of generators. These devices are then classified according to the way the bubbling process is controlled: outer liquid flows (e.g., coflows, cross flows, and flow-focusing flows), acoustic forcing, and electric fields. We also address modern techniques developed to produce bubbles coated with surfactants and liquid shells. The stringent requirements to precisely control the bubbling frequency, the bubble size, and the properties of the coating make microfluidics the natural choice to implement such techniques.

Rise of Air Bubbles in Aircraft Lubricating Oils

NASA Technical Reports Server (NTRS)

Robinson, J. V.

1950-01-01

Lubricating and antifoaming additives in aircraft lubricating oils may impede the escape of small bubbles from the oil by forming shells of liquid with a quasi-solid or gel structure around the bubbles. The rates of rise of small air bubbles, up to 2 millimeters in diameter, were measured at room temperature in an undoped oil, in the same oil containing foam inhibitors, and in an oil containing lubricating additives. The apparent diameter of the air bubbles was measured visually through an ocular micrometer on a traveling telescope. The bubbles in the undoped oil obeyed Stokes' Law, the rate of rise being proportional to the square of the apparent diameter and inversely proportional to the viscosity of the oil. The bubbles in the oils containing lubricating additives or foam inhibitors rose more slowly than the rate predicted by Stokes 1 Law from the apparent diameter, and the rate of rise decreased as the length of path the bubbles traveled increased. A method is derived to calculate the thickness of the liquid shell which would have to move with the bubbles in the doped oils to account for the abnoi'I!l8.lly slow velocity. The maximum thickness of this shell, calculated from the velocities observed, was equal to the bubble radius.

Modelling of Dispersed Gas-Liquid Flow using LBGK and LPT Approach

NASA Astrophysics Data System (ADS)

Agarwal, Alankar; Prakash, Akshay; Ravindra, B.

2017-11-01

The dynamics of gas bubbles play a significant, if not crucial, role in a large variety of industrial process that involves using reactors. Many of these processes are still not well understood in terms of optimal scale-up strategies.An accurate modeling of bubbles and bubble swarms become important for high fidelity bioreactor simulations. This study is a part of the development of robust bubble fluid interaction modules for simulation of industrial-scale reactors. The work presents the simulation of a single bubble rising in a quiescent water tank using current models presented in the literature for bubble-fluid interaction. In this multiphase benchmark problem, the continuous phase (water) is discretized using the Lattice Bhatnagar-Gross and Krook (LBGK) model of Lattice Boltzmann Method (LBM), while the dispersed gas phase (i.e. air-bubble) modeled with the Lagrangian particle tracking (LPT) approach. The cheap clipped fourth order polynomial function is used to model the interaction between two phases. The model is validated by comparing the simulation results for terminal velocity of a bubble at varying bubble diameter and the influence of bubble motion in liquid velocity with the theoretical and previously available experimental data. This work is supported by the ``Centre for Development of Advanced Computing (C-DAC), Pune'' by providing the advanced computational facility in PARAM Yuva-II.

New solutions for steady bubbles in a Hele-Shaw cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanveer, S.

1987-03-01

Exact solutions are presented for steadily moving bubbles in a Hele--Shaw cell when the effect of surface tension is neglected. These solutions form a three-parameter family. For specified area, both the speed of the bubble and the distance of its centroid from the channel centerline remain arbitrary when surface tension is ignored. However, numerical evidence suggests that this twofold arbitrariness is removed by the effect of surface tension, i.e., for given bubble area and surface tension, solutions exist only when the bubble velocity and the centroid distance from the channel centerline attain one or more isolated values. From a limitedmore » numerical search, no nonsymmetric solutions could be found; however, a branch of symmetric bubble solutions that was not found in earlier work was found. This branch corresponds to one of the Romero-Vanden-Broeck branch of finger solutions when the bubble size is large. A new procedure for numerical calculations of bubble solutions in the presence of surface tension is presented and is found to work very well for reasonably large bubbles, unlike the previous method of Tanveer (Phys. Fluids 29, 3537 (1986)). The precise power law dependence of bubble velocity on surface tension for small surface tension is explored for bubbles of different area. Agreement is noted with recent analytical results for a finger.« less

Formation mechanism of gas bubble superlattice in UMo metal fuels: Phase-field modeling investigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Shenyang; Burkes, Douglas E.; Lavender, Curt A.

2016-07-08

Nano-gas bubble superlattices are often observed in irradiated UMo nuclear fuels. However, the for- mation mechanism of gas bubble superlattices is not well understood. A number of physical processes may affect the gas bubble nucleation and growth; hence, the morphology of gas bubble microstructures including size and spatial distributions. In this work, a phase-field model integrating a first-passage Monte Carlo method to investigate the formation mechanism of gas bubble superlattices was devel- oped. Six physical processes are taken into account in the model: 1) heterogeneous generation of gas atoms, vacancies, and interstitials informed from atomistic simulations; 2) one-dimensional (1-D) migration of interstitials; 3) irradiation-induced dissolution of gas atoms; 4) recombination between vacancies and interstitials; 5) elastic interaction; and 6) heterogeneous nucleation of gas bubbles. We found that the elastic interaction doesn’t cause the gas bubble alignment, and fast 1-D migration of interstitials alongmore » $$\\langle$$110$$\\rangle$$ directions in the body-centered cubic U matrix causes the gas bubble alignment along $$\\langle$$110$$\\rangle$$ directions. It implies that 1-D interstitial migration along [110] direction should be the primary mechanism of a fcc gas bubble superlattice which is observed in bcc UMo alloys. Simulations also show that fission rates, saturated gas concentration, and elastic interaction all affect the morphology of gas bubble microstructures.« less

The Bubble Box: Towards an Automated Visual Sensor for 3D Analysis and Characterization of Marine Gas Release Sites.

PubMed

Jordt, Anne; Zelenka, Claudius; von Deimling, Jens Schneider; Koch, Reinhard; Köser, Kevin

2015-12-05

Several acoustic and optical techniques have been used for characterizing natural and anthropogenic gas leaks (carbon dioxide, methane) from the ocean floor. Here, single-camera based methods for bubble stream observation have become an important tool, as they help estimating flux and bubble sizes under certain assumptions. However, they record only a projection of a bubble into the camera and therefore cannot capture the full 3D shape, which is particularly important for larger, non-spherical bubbles. The unknown distance of the bubble to the camera (making it appear larger or smaller than expected) as well as refraction at the camera interface introduce extra uncertainties. In this article, we introduce our wide baseline stereo-camera deep-sea sensor bubble box that overcomes these limitations, as it observes bubbles from two orthogonal directions using calibrated cameras. Besides the setup and the hardware of the system, we discuss appropriate calibration and the different automated processing steps deblurring, detection, tracking, and 3D fitting that are crucial to arrive at a 3D ellipsoidal shape and rise speed of each bubble. The obtained values for single bubbles can be aggregated into statistical bubble size distributions or fluxes for extrapolation based on diffusion and dissolution models and large scale acoustic surveys. We demonstrate and evaluate the wide baseline stereo measurement model using a controlled test setup with ground truth information.

The Bubble Box: Towards an Automated Visual Sensor for 3D Analysis and Characterization of Marine Gas Release Sites

PubMed Central

Jordt, Anne; Zelenka, Claudius; Schneider von Deimling, Jens; Koch, Reinhard; Köser, Kevin

2015-01-01

Several acoustic and optical techniques have been used for characterizing natural and anthropogenic gas leaks (carbon dioxide, methane) from the ocean floor. Here, single-camera based methods for bubble stream observation have become an important tool, as they help estimating flux and bubble sizes under certain assumptions. However, they record only a projection of a bubble into the camera and therefore cannot capture the full 3D shape, which is particularly important for larger, non-spherical bubbles. The unknown distance of the bubble to the camera (making it appear larger or smaller than expected) as well as refraction at the camera interface introduce extra uncertainties. In this article, we introduce our wide baseline stereo-camera deep-sea sensor bubble box that overcomes these limitations, as it observes bubbles from two orthogonal directions using calibrated cameras. Besides the setup and the hardware of the system, we discuss appropriate calibration and the different automated processing steps deblurring, detection, tracking, and 3D fitting that are crucial to arrive at a 3D ellipsoidal shape and rise speed of each bubble. The obtained values for single bubbles can be aggregated into statistical bubble size distributions or fluxes for extrapolation based on diffusion and dissolution models and large scale acoustic surveys. We demonstrate and evaluate the wide baseline stereo measurement model using a controlled test setup with ground truth information. PMID:26690168

Protein Adsorption Alters Hydrophobic Surfaces Used for Suspension Culture of Pluripotent Stem Cells.

PubMed

Jonas, Steven J; Stieg, Adam Z; Richardson, Wade; Guo, Shuling; Powers, David N; Wohlschlegel, James; Dunn, Bruce

2015-02-05

This Letter examines the physical and chemical changes that occur at the interface of methyl-terminated alkanethiol self-assembled monolayers (SAMs) after exposure to cell culture media used to derive embryoid bodies (EBs) from pluripotent stem cells. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy analysis of the SAMs indicates that protein components within the EB cell culture medium preferentially adsorb at the hydrophobic interface. In addition, we examined the adsorption process using surface plasmon resonance and atomic force microscopy. These studies identify the formation of a porous, mat-like adsorbed protein film with an approximate thickness of 2.5 nm. Captive bubble contact angle analysis reveals a shift toward superhydrophilic wetting behavior at the cell culture interface due to adsorption of these proteins. These results show how EBs are able to remain in suspension when derived on hydrophobic materials, which carries implications for the rational design of suspension culture interfaces for lineage specific stem-cell differentiation.

Captive-breeding of captive and wild-reared Gunnison sage-grouse.

PubMed

Apa, Anthony D; Wiechman, Lief A

2016-01-01

Gunnison sage-grouse (Centrocercus minimus) distribution in North America has decreased over historical accounts and has received federal protection under the Endangered Species Act. We investigated captive-breeding of a captive-flock of Gunnison sage-grouse created from individuals reared in captivity from wild-collected eggs we artificially incubated. We also introduced wild-reared individuals into captivity. Our captive-flock successfully bred and produced fertile eggs. We controlled the timing and duration of male-female breeding interactions and facilitated a semi-natural mating regime. Males established a strutting ground in captivity that females attended for mate selection. In 2010, we allowed females to establish eight nests, incubate, and hatch eggs. Females in captivity were more successful incubating nests than raising broods. Although there are many technical, financial, and logistic issues associated with captive-breeding, we recommend that federal biologists and managers work collaboratively with state wildlife agencies and consider developing a captive-flock as part of a comprehensive conservation strategy for a conservation-reliant species like the Gunnison sage-grouse. The progeny produced from a captive-rearing program could assist in the recovery if innovative approaches to translocation are part of a comprehensive proactive conservation program. © 2015 Wiley Periodicals, Inc.

Study on drag coefficient of rising bubble in still water

NASA Astrophysics Data System (ADS)

Shi, M. Y.; Qi, Mei; Yi, C. G.; Liu, D. Y.; Zhang, K. X.

2017-09-01

Research on the behavior of a rising bubble in still water is on the basis of Newton's theory of classical mechanics. Develop a calculation analysis and an experimental process of bubble rising behavior in order to search for an appropriate way of valuing drag coefficient, which is the key element toward this issue. Analyze the adaptability of the drag coefficient; compare the theoretical model to the real experimental model of rising bubble behavior. The result turns out that the change rate of radius could be ignored according to the analysis; the acceleration phase is transient; final velocity and the diameter of bubble do relate to the drag coefficient, but have no obvious relation with the depth of water. After series of inference analysis of the bubble behavior and experimental demonstration, a new drag coefficient and computing method is proposed.

Establishment of a total liquid ventilation system using saline-based oxygen micro/nano-bubble dispersions in rats.

PubMed

Kakiuchi, Kenta; Matsuda, Kenichi; Harii, Norikazu; Sou, Keitaro; Aoki, Junko; Takeoka, Shinji

2015-09-01

Micro/nano-bubbles are practical nanomaterials designed to increase the gas content in liquids. We attempted to use oxygen micro/nano-bubble dispersions as an oxygen-rich liquid as a means for total liquid ventilation. To determine the oxygen content in the bubble dispersion, a new method based on a spectrophotometric change between oxy- and deoxy-hemoglobin was established. The oxygen micro/nano-bubble dispersion was supplied to an experimental total ventilation liquid in anesthetic rats. Though the amount of dissolving oxygen was as low as 6 mg/L in physiological saline, the oxygen content in the oxygen micro/nano-bubble dispersion was increased to 45 mg/L. The positive correlation between the oxygen content and the life-saving time under liquid ventilation clearly indicates that the life-saving time is prolonged by increasing the oxygen content in the oxygen micro/nano-bubble dispersion. This is the first report indicating that the oxygen micro/nano-bubbles containing a sufficient amount of oxygen are useful in producing oxygen-rich liquid for the process of liquid ventilation.

An investigation of bubble coalescence and post-rupture oscillation in non-ionic surfactant solutions using high-speed cinematography.

PubMed

Bournival, G; Ata, S; Karakashev, S I; Jameson, G J

2014-01-15

Most processes involving bubbling in a liquid require small bubbles to maximise mass/energy transfer. A common method to prevent bubbles from coalescing is by the addition of surfactants. In order to get an insight into the coalescence process, capillary bubbles were observed using a high speed cinematography. Experiments were performed in solutions of 1-pentanol, 4-methyl-2-pentanol, tri(propylene glycol) methyl ether, and poly(propylene glycol) for which information such as the coalescence time and the deformation of the resultant bubble upon coalescence was extracted. It is shown in this study that the coalescence time increases with surfactant concentration until the appearance of a plateau. The increase in coalescence time with surfactant concentration could not be attributed only to surface elasticity. The oscillation of the resultant bubble was characterised by the damping of the oscillation. The results suggested that a minimum elasticity is required to achieve an increased damping and considerable diffusion has a detrimental effect on the dynamic response of the bubble, thereby reducing the damping. Copyright © 2013 Elsevier Inc. All rights reserved.

Automated Laser-Light Scattering measurements of Impurities, Bubbles, and Imperfections in Ice Cores

NASA Astrophysics Data System (ADS)

Stolz, M. R.; Ram, M.

2004-12-01

Laser- light scattering (LLS) on polar ice, or on polar ice meltwater, is an accepted method for measuring the concentration of water insoluble aerosol deposits (dust) in the ice. LLS on polar ice can also be used to measure water soluble aerosols, as well as imperfections (air bubbles and cavities) in the ice. LLS was originally proposed by Hammer (1977a, b) as a method for measuring the dust concentration in polar ice meltwater. Ram et al. (1995) later advanced the method and applied it to solid ice, measuring the dust concentration profile along the deep, bubble-free sections of the Greenland Ice Sheet Projetct 2 (GISP2) ice core (Ram et al., 1995, 2000) from central Greenland. In this paper, we will put previous empirical findings (Ram et al., 1995, 2000) on a theoretical footing, and extend the usability of LLS on ice into the realm of the non-transparent, bubbly polar ice. For LLS on clear, bubble-free polar ice, we studied numerically the scattering of light by soluble and insoluble (dust) aerosol particles embedded in the ice to complement previous experimental studies (Ram et al., 2000). For air bubbles in polar ice, we calculated the effects of multiple light scattering using Mie theory and Monte Carlo simulations, and found a method for determining the bubble number size and concentration using LLS on bubbly ice. We also demonstrated that LLS can be used on bubbly ice to measure annual layers rapidly in an objective manner. Hammer, C. U. (1977a), Dating of Greenland ice cores by microparticle concentration analyses., in International Symposium on Isotopes and Impurities in Snow and Ice, pp. 297-301, IAHS publ. no. 118. Hammer, C. U. (1977b), Dust studies on Greenland ice cores, in International Symposium on Isotopes and Impurities in Snow and Ice, pp. 365-370, IAHS publ. no. 118. Ram, M., M. Illing, P. Weber, G. Koenig, and M. Kaplan (1995), Polar ice stratigraphy from laser-light scattering: Scattering from ice, Geophys. Res. Lett., 22(24), 3525-3527. Ram, M., J. Donarummo, M. R. Stolz, and G. Koenig (2000), Calibration of laser-light scattering measurements of dust concentration for Wisconsinan GISP2 ice using instrumental neutron activation analysis of aluminum: Results and discussion, J. Geophys. Res., 105(D20), 24,731--24,738.

Application of analyzer based X-ray imaging technique for detection of ultrasound induced cavitation bubbles from a physical therapy unit.

PubMed

Izadifar, Zahra; Belev, George; Babyn, Paul; Chapman, Dean

2015-10-19

The observation of ultrasound generated cavitation bubbles deep in tissue is very difficult. The development of an imaging method capable of investigating cavitation bubbles in tissue would improve the efficiency and application of ultrasound in the clinic. Among the previous imaging modalities capable of detecting cavitation bubbles in vivo, the acoustic detection technique has the positive aspect of in vivo application. However the size of the initial cavitation bubble and the amplitude of the ultrasound that produced the cavitation bubbles, affect the timing and amplitude of the cavitation bubbles' emissions. The spatial distribution of cavitation bubbles, driven by 0.8835 MHz therapeutic ultrasound system at output power of 14 Watt, was studied in water using a synchrotron X-ray imaging technique, Analyzer Based Imaging (ABI). The cavitation bubble distribution was investigated by repeated application of the ultrasound and imaging the water tank. The spatial frequency of the cavitation bubble pattern was evaluated by Fourier analysis. Acoustic cavitation was imaged at four different locations through the acoustic beam in water at a fixed power level. The pattern of cavitation bubbles in water was detected by synchrotron X-ray ABI. The spatial distribution of cavitation bubbles driven by the therapeutic ultrasound system was observed using ABI X-ray imaging technique. It was observed that the cavitation bubbles appeared in a periodic pattern. The calculated distance between intervals revealed that the distance of frequent cavitation lines (intervals) is one-half of the acoustic wave length consistent with standing waves. This set of experiments demonstrates the utility of synchrotron ABI for visualizing cavitation bubbles formed in water by clinical ultrasound systems working at high frequency and output powers as low as a therapeutic system.

Efficacy of Blunt Force Trauma, a Novel Mechanical Cervical Dislocation Device, and a Non-Penetrating Captive Bolt Device for On-Farm Euthanasia of Pre-Weaned Kits, Growers, and Adult Commercial Meat Rabbits

PubMed Central

Walsh, Jessica L.; Percival, Aaron

2017-01-01

Simple Summary Developing effective and humane on-farm euthanasia methods is essential for all livestock industries to ensure that animals do not suffer and are killed humanely. Approved methods are lacking for commercial meat rabbits, potentially leading to poor welfare. We assessed several methods of on-farm killing of cull rabbits of different ages to determine which methods were most effective and humane. These included blunt force trauma (the most commonly used method on rabbit farms), a novel mechanical cervical dislocation device, and a non-penetrating captive bolt device. We evaluated method effectiveness by examining animal reflexes and behaviours after applying the method as well as by examining radiographs of rabbit heads for signs of skull damage, and by assessing the degree of trauma to the brain through dissection and microscopy, because more trauma is generally correlated with enhanced method effectiveness and irreversibility. We found that blunt force trauma resulted in an unacceptably high failure rate, particularly in mature rabbits, whereas the mechanical cervical dislocation and non-penetrating captive bolt devices were both highly effective for killing rabbits humanely and irreversibly. The non-penetrating captive bolt device was the most effective with a 100% success rate and could be used on all rabbits weighing more than 150 g. Abstract The commercial meat rabbit industry is without validated on-farm euthanasia methods, potentially resulting in inadequate euthanasia protocols. We evaluated blunt force trauma (BFT), a mechanical cervical dislocation device (MCD), and a non-penetrating captive bolt device (NPCB) for euthanasia of pre-weaned kits, growers, and adult rabbits. Trials were conducted on three commercial meat rabbit farms using 170 cull rabbits. Insensibility was assessed by evaluating absence of brainstem and spinal reflexes, rhythmic breathing, and vocalizations. Survey radiographs on a subsample of rabbits (n = 12) confirmed tissue damage prior to gross dissection and microscopic evaluation. All 63 rabbits euthanized by the NPCB device were rendered immediately and irreversibly insensible. The MCD device was effective in 46 of 49 (94%) rabbits. Method failure was highest for BFT with euthanasia failures in 13 of 58 (22%) rabbits. Microscopically, brain sections from rabbits killed with the NPCB device had significantly more damage than those from rabbits killed with BFT (p = 0.001). We conclude that BFT is neither consistently humane nor effective as a euthanasia method. MCD is an accurate and reliable euthanasia method generally causing clean dislocation and immediate and irreversible insensibility, and the NPCB device was 100% effective and reliable in rabbits >150 g. PMID:29244782

Interaction of a vortex ring and a bubble

NASA Astrophysics Data System (ADS)

Jha, Narsing K.; Govardhan, Raghuraman N.

2014-11-01

Micro-bubble injection in to boundary layers is one possible method for reducing frictional drag of ships. Although this has been studied for some time, the physical mechanisms responsible for drag reduction using microbubbles in turbulent boundary layers is not yet fully understood. Previous studies suggest that bubble-vortical structure interaction seems to be one of the important physical mechanisms for frictional drag reduction using microbubbles. In the present work, we study a simplification of this problem, namely, the interaction of a single vortical structure, in particular a vortex ring, with a single bubble for better understanding of the physics. The vortex ring is generated using a piston-cylinder arrangement and the bubble is generated by connecting a capillary to an air pump. The bubble dynamics is directly visualized using a high speed camera, while the vorticity modification is measured using time resolved PIV. The results show that significant deformations can occur of both the bubble and the vortex ring. Effect of different non-dimensional parameters on the interaction will be presented in the meeting.

Small-bubble transport and splitting dynamics in a symmetric bifurcation.

PubMed

Qamar, Adnan; Warnez, Matthew; Valassis, Doug T; Guetzko, Megan E; Bull, Joseph L

2017-08-01

Simulations of small bubbles traveling through symmetric bifurcations are conducted to garner information pertinent to gas embolotherapy, a potential cancer treatment. Gas embolotherapy procedures use intra-arterial bubbles to occlude tumor blood supply. As bubbles pass through bifurcations in the blood stream nonhomogeneous splitting and undesirable bioeffects may occur. To aid development of gas embolotherapy techniques, a volume of fluid method is used to model the splitting process of gas bubbles passing through artery and arteriole bifurcations. The model reproduces the variety of splitting behaviors observed experimentally, including the bubble reversal phenomenon. Splitting homogeneity and maximum shear stress along the vessel walls is predicted over a variety of physical parameters. Small bubbles, having initial length less than twice the vessel diameter, were found unlikely to split in the presence of gravitational asymmetry. Maximum shear stresses were found to decrease exponentially with increasing Reynolds number. Vortex-induced shearing near the bifurcation is identified as a possible mechanism for endothelial cell damage.

Evaluation of Interfacial Forces and Bubble-Induced Turbulence Using Direct Numerical Simulation

NASA Astrophysics Data System (ADS)

Feng, Jinyong

High fidelity prediction of multiphase flows is important in a wide range of engineering applications. While some multiphase flow scenarios can be successfully modeled, many questions remain unanswered regarding the interaction between the bubbles and the turbulence, and present significant challenges in the development of closure laws for the multiphase computational fluid dynamics (M-CFD) models. To address these challenges, we propose to evaluate the interfacial forces and bubble-induced turbulence in both laminar and turbulent flow field with direct numerical simulation (DNS) approach. Advanced finite-element based flow solver (PHASTA) with level-set interface tracking method is utilized for these studies. The proportional-integral-derivative (PID) controller is adopted to ensure the statistically steady state bubble position and perform the detailed study of the turbulent field around the bubble. Selected numerical capabilities and post-processing codes are developed to achieve the research goals. The interface tracking approach is verified and validated by comparing the interfacial forces with the experiment-based data and correlations. The sign change of transverse lift force is observed as the bubble becomes more deformable. A new correlation is proposed to predict the behavior of the drag coefficient over the wide range of conditions. The wall effect on the interfacial forces are also investigated. In homogeneous turbulent flow, the effect of bubble deformability, turbulent intensity and relative velocity on the bubble-induced turbulence are analyzed. The presented method and novel results will complement the experimental database, provide insight to the bubbleinduced turbulence mechanism and help the development of M-CFD closure models.

Brief communication: Hip joint mobility in free-ranging rhesus macaques

PubMed Central

Hammond, Ashley S.; Johnson, Victoria P.; Higham, James P.

2016-01-01

Objectives We aimed to test for differences in hip joint range of motion (ROM) between captive and free-ranging rhesus macaques (Macaca mulatta), particularly for hip joint abduction, which previous studies of captive macaques have found to be lower than predicted. Materials and Methods Hip ROM was assessed following standard joint measurement methodology in anesthetized adult free-ranging rhesus macaques (n=39) from Cayo Santiago, and compared to published ROM data from captive rhesus macaques (n=16) (Hammond 2014a, American Journal of Physical Anthropology). Significant differences between populations were detected using one-way analysis of variance (p<0.05). Results In a sample of pooled sexes and ages, free-ranging macaques are capable of increased hip abduction, flexion, and internal rotation compared to captive individuals. These differences in joint excursion resulted in free-ranging individuals having significantly increased ROM for hip adduction-abduction, rotation, flexion-extension, and the distance spanned by the knee during hip abduction. When looking at data for a smaller sample of age-matched males, fewer ROM differences are significant, but free-ranging males have significantly increased hip abduction, internal rotation, range of flexion-extension, and distance spanned by the knee during hip abduction compared to captive males of similar age. Discussion Our results suggest that a spatially restrictive environment results in decreased hip mobility in cage-confined animals and ultimately limits the potential limb postures in captive macaques. These results have implications for selection of animal samples in model validation studies, as well as laboratory animal husbandry practices. PMID:27731892

An Empirical Derivation of the Run Time of the Bubble Sort Algorithm.

ERIC Educational Resources Information Center

Gonzales, Michael G.

1984-01-01

Suggests a moving pictorial tool to help teach principles in the bubble sort algorithm. Develops such a tool applied to an unsorted list of numbers and describes a method to derive the run time of the algorithm. The method can be modified to run the times of various other algorithms. (JN)

Study on Prediction of Underwater Radiated Noise from Propeller Tip Vortex Cavitation

NASA Astrophysics Data System (ADS)

Yamada, Takuyoshi; Sato, Kei; Kawakita, Chiharu; Oshima, Akira

2015-12-01

The method to predict underwater radiated noise from tip vortex cavitation was studied. The growth of a single cavitation bubble in tip vortex was estimated by substituting the tip vortex to Rankine combined vortex. The ideal spectrum function for the sound pressure generated by a single cavitation bubble was used, also the empirical factor for the number of collapsed bubbles per unit time was introduced. The estimated noise data were compared with measured ship's ones and it was found out that this method can estimate noise data within 3dB difference.

Comparison of two different methods of preoperative marking for toric intraocular lens implantation: bubble marker versus pendulum marker

PubMed Central

Farooqui, Javed Hussain; Koul, Archana; Dutta, Ranjan; Shroff, Noshir Minoo

2016-01-01

AIM To compare the accuracy of two different methods of preoperative marking for toric intraocular lens (IOL) implantation, bubble marker versus pendulum marker, as a means of establishing the reference point for the final alignment of the toric IOL to achieve an outcome as close as possible to emmetropia. METHODS Toric IOLs were implanted in 180 eyes of 110 patients. One group (55 patients) had preoperative marking of both eyes done with bubble marker (ASICO AE-2791TBL) and the other group (55 patients) with pendulum marker (Rumex®3-193). Reference marks were placed at 3-, 6-, and 9-o'clock positions on the limbus. Slit-lamp photographs were analyzed using Adobe Photoshop (version 7.0). Amount of alignment error (in degrees) induced in each group was measured. RESULTS Mean absolute rotation error in the preoperative marking in the horizontal axis was 2.42±1.71 in the bubble marker group and 2.83±2.31in the pendulum marker group (P=0.501). Sixty percent of the pendulum group and 70% of the bubble group had rotation error ≤3 (P=0.589), and 90% eyes of the pendulum group and 96.7% of the bubble group had rotation error ≤5 (P=0.612). CONCLUSION Both preoperative marking techniques result in approximately 3 of alignment error. Both marking techniques are simple, predictable, reproducible and easy to perform. PMID:27275425

Impact sensitivity test of liquid energetic materials

NASA Astrophysics Data System (ADS)

Tiutiaev, A.; Dolzhikov, A.; Zvereva, I.

2017-10-01

This paper presents new experimental method for sensitivity evaluation at the impact. A large number of researches shown that the probability of explosion initiating of liquid explosives by impact depends on the chemical nature and the various external characteristics. But the sensitivity of liquid explosive in the presence of gas bubbles increases many times as compared with the liquid without gas bubbles. In this case local chemical reaction focus are formed as a result of compression and heating of the gas inside the bubbles. In the liquid as a result of convection, wave motion, shock, etc. gas bubbles are easily generated, it is necessary to develop methods for determining sensitivity of liquid explosives to impact and to research the explosives ignition with bubbles. For the experimental investigation, the well-known impact machine and the so-called appliance 1 were used. Instead of the metal cup in the standard method in this paper polyurethane foam cylindrical container with liquid explosive was used. Polyurethane foam cylindrical container is easily deforms by impact. A large number of tests with different liquid explosives were made. It was found that the test liquid explosive to impact in appliance 1 with polyurethane foam to a large extent reflect the real mechanical sensitivity due to the small loss of impact energy on the deformation of the metal cup, as well as the best differentiation liquid explosive sensitivity due to the higher resolution method.

Experimental investigation on dynamic characteristics and strengthening mechanism of laser-induced cavitation bubbles.

PubMed

Ren, X D; He, H; Tong, Y Q; Ren, Y P; Yuan, S Q; Liu, R; Zuo, C Y; Wu, K; Sui, S; Wang, D S

2016-09-01

The dynamic features of nanosecond laser-induced cavitation bubbles near the light alloy boundary were investigated with the high-speed photography. The shock-waves and the dynamic characteristics of the cavitation bubbles generated by the laser were detected using the hydrophone. The dynamic features and strengthening mechanism of cavitation bubbles were studied. The strengthening mechanisms of cavitation bubble were discussed when the relative distance parameter γ was within the range of 0.5-2.5. It showed that the strengthening mechanisms caused by liquid jet or shock-waves depended on γ much. The research results provided a new strengthening method based on laser-induced cavitation shotless peening (CSP). Copyright © 2016 Elsevier B.V. All rights reserved.

Transient bubbles, bublets and breakup

NASA Astrophysics Data System (ADS)

Keen, Giles; Blake, John

1999-11-01

The non-spherical nature of the collapse of bubbles has important ramifications in many practical situations such as ultrasonic cleaning, tanning of leather, and underwater explosions. In particular the high speed liquid jet that can thread a collapsing bubble is central to the functional performance. An impressive photographic record of a liquid jet was obtained by Crum using a bubble situated in the vicinity of a platform oscillating vertically at a frequency of 60 Hz. A boundary integral method is used to model this situation and is found to closely mimic some of the observations. However, a slight variation of parameters or a change in the phase of the driving frequency can lead to dramatically different bubble behaviour, a feature also observed by Crum.

NEPHROPATHIES IN THE EUROPEAN CAPTIVE CHEETAH (ACINONYX JUBATUS) POPULATION.

PubMed

Url, Angelika; Krutak, Verena; Kübber-Heiss, Anna; Chvala-Mannsberger, Sonja; Robert, Nadia; Dinhopl, Nora; Schmidt, Peter; Walzer, Chris

2016-09-01

According to previous studies in captive cheetah ( Acinonyx jubatus ) populations, one of the most threatening diseases besides amyloidosis, myelopathy, veno occlusive disease, and gastritis, is renal failure. Contrary to captive cheetahs in North America and South Africa, morphological data concerning renal lesions in the cheetah European Endangered Species Program (EEP) are lacking. This study details the histological characterization as well as immunohistochemical and morphometrical analysis of nephropathies in 35 captive cheetahs from the EEP, which were necropsied between 1985 and 2003. Examination of paraffin- and glycolmethacrylate-methylmethacrylate (GMA-MMA) embedded kidney samples by light microscopy revealed glomerulonephritis in 91%, with a high prevalence for glomerulosclerosis and glomerulonephritis with the histologic pattern of membranous glomerulonephritis (77%). Besides these predominating glomerulopathies, a wide range of other renal lesions, like acute tubular necrosis, interstitial nephritis, calcinosis, and amyloidosis, were present. Pathological expression of collagen type IV, complement C3, fibronectin, and IgG was demonstrated in the glomeruli of the cheetah kidneys with the use of the avidin-biotin complex method. Morphometrical analysis was performed on GMA-MMA embedded kidney samples to obtain glomerulosclerosis index and glomerulosclerosis incidence.

Dynamics of vapor bubbles growth at boiling resulting from enthalpy excess of the surrounding superheated liquid and sound pulses generated by bubbles

NASA Astrophysics Data System (ADS)

Dorofeev, B. M.; Volkova, V. I.

2016-01-01

The results of experiments investigating the exponential dependence of the vapor bubble radius on time at saturated boiling are generalized. Three different methods to obtain this dependence are suggested: (1) by the application of the transient heat conduction equation, (2) by using the correlations of energy conservation, and (3) by solving a similar electrodynamic problem. Based on the known experimental data, the accuracy of the dependence up to one percent and a few percent accuracy of its description based on the sound pressure generated by a vapor bubble have been determined. A significant divergence of the power dependence of the vapor bubble radius on time (with an exponent of 1/2) with the experimental results and its inadequacy for the description of the sound pulse generated by the bubble have been demonstrated.

Thermodynamics of ultra-sonic cavitation bubbles in flotation ore processes

NASA Astrophysics Data System (ADS)

Royer, J. J.; Monnin, N.; Pailot-Bonnetat, N.; Filippov, L. O.; Filippova, I. V.; Lyubimova, T.

2017-07-01

Ultra-sonic enhanced flotation ore process is a more efficient technique for ore recovery than classical flotation method. A classical simplified analytical Navier-Stokes model is used to predict the effect of the ultrasonic waves on the cavitations bubble behaviour. Then, a thermodynamics approach estimates the temperature and pressure inside a bubble, and investigates the energy exchanges between flotation liquid and gas bubbles. Several gas models (including ideal gas, Soave-Redlich-Kwong, and Peng-Robinson) assuming polytropic transformations (from isothermal to adiabatic) are used to predict the evolution of the internal pressure and temperature inside the bubble during the ultrasonic treatment, together with the energy and heat exchanges between the gas and the surrounding fluid. Numerical simulation illustrates the suggest theory. If the theory is verified experimentally, it predicts an increase of the temperature and pressure inside the bubbles. Preliminary ultrasonic flotation results performed on a potash ore seem to confirm the theory.

Compression-induced stacking fault tetrahedra around He bubbles in Al

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shao, Jian-Li, E-mail: shao-jianli@iapcm.ac.cn; Wang, Pei; He, An-Min

Classic molecular dynamics methods are used to simulate the uniform compression process of the fcc Al containing He bubbles. The formation of stacking fault tetrahedra (SFTs) during the collapse of He bubbles is found, and their dependence on the initial He bubble size (0.6–6 nm in diameter) is presented. Our simulations indicate only elastic deformation in the samples for the He bubble size not more than 2 nm. Instead, increasing the He bubble size, we detect several small SFTs forming on the surface of the He bubble (3 nm), as well as the two intercrossed SFTs around the He bubbles (4–6 nm). All thesemore » SFTs are observed to be stable under further compression, though there may appear some SF networks outside the SFTs (5–6 nm). Furthermore, the dynamic analysis on the SFTs shows that the yield pressure keeps a near-linear increase with the initial He bubble pressure, and the potential energy of Al atoms inside the SFTs is lower than outside because of their gliding inwards. In addition, the pressure increments of 2–6 nm He bubbles with strain are less than that of Al, which just provides the opportunity for the He bubble collapse and the SFTs formation. Note that the current work only focuses on the case that the number ratio between He atoms and Al vacancies is 1:1.« less

Stream-wise distribution of skin-friction drag reduction on a flat plate with bubble injection

NASA Astrophysics Data System (ADS)

Qin, Shijie; Chu, Ning; Yao, Yan; Liu, Jingting; Huang, Bin; Wu, Dazhuan

2017-03-01

To investigate the stream-wise distribution of skin-friction drag reduction on a flat plate with bubble injection, both experiments and simulations of bubble drag reduction (BDR) have been conducted in this paper. Drag reductions at various flow speeds and air injection rates have been tested in cavitation tunnel experiments. Visualization of bubble flow pattern is implemented synchronously. The computational fluid dynamics (CFD) method, in the framework of Eulerian-Eulerian two fluid modeling, coupled with population balance model (PBM) is used to simulate the bubbly flow along the flat plate. A wide range of bubble sizes considering bubble breakup and coalescence is modeled based on experimental bubble distribution images. Drag and lift forces are fully modeled based on applicable closure models. Both predicted drag reductions and bubble distributions are in reasonable concordance with experimental results. Stream-wise distribution of BDR is revealed based on CFD-PBM numerical results. In particular, four distinct regions with different BDR characteristics are first identified and discussed in this study. Thresholds between regions are extracted and discussed. And it is highly necessary to fully understand the stream-wise distribution of BDR in order to establish a universal scaling law. Moreover, mechanism of stream-wise distribution of BDR is analysed based on the near-wall flow parameters. The local drag reduction is a direct result of near-wall max void fraction. And the near-wall velocity gradient modified by the presence of bubbles is considered as another important factor for bubble drag reduction.

A hydrodynamical model of the circumstellar bubble created by two massive stars

NASA Astrophysics Data System (ADS)

van Marle, A. J.; Meliani, Z.; Marcowith, A.

2012-05-01

Context. Numerical models of the wind-blown bubble of massive stars usually only account for the wind of a single star. However, since massive stars are usually formed in clusters, it would be more realistic to follow the evolution of a bubble created by several stars. Aims: We develop a two-dimensional (2D) model of the circumstellar bubble created by two massive stars, a 40 M⊙ star and a 25 M⊙ star, and follow its evolution. The stars are separated by approximately 16 pc and surrounded by a cold medium with a density of 20 particles per cm3. Methods: We use the MPI-AMRVAC hydrodynamics code to solve the conservation equations of hydrodynamics on a 2D cylindrical grid using time-dependent models for the wind parameters of the two stars. At the end of the stellar evolution (4.5 and 7.0 million years for the 40 and 25 M⊙ stars, respectively), we simulate the supernova explosion of each star. Results: Each star initially creates its own bubble. However, as the bubbles expand they merge, creating a combined, aspherical bubble. The combined bubble evolves over time, influenced by the stellar winds and supernova explosions. Conclusions: The evolution of a wind-blown bubble created by two stars deviates from that of the bubbles around single stars. In particular, once one of the stars has exploded, the bubble is too large for the wind of the remaining star to maintain and the outer shell starts to disintegrate. The lack of thermal pressure inside the bubble also changes the behavior of circumstellar features close to the remaining star. The supernovae are contained inside the bubble, which reflects part of the energy back into the circumstellar medium. Movies are available in electronic form at http://www.aanda.org

Contactless Inductive Bubble Detection in a Liquid Metal Flow

PubMed Central

Gundrum, Thomas; Büttner, Philipp; Dekdouk, Bachir; Peyton, Anthony; Wondrak, Thomas; Galindo, Vladimir; Eckert, Sven

2016-01-01

The detection of bubbles in liquid metals is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The high electrical conductivity of the liquid metal can be exploited for contactless methods based on electromagnetic induction. We will present a measurement system which consists of one excitation coil and a pickup coil system on the opposite sides of the pipe. With this sensor we were able to detect bubbles in a sodium flow inside a stainless steel pipe and bubbles in a column filled with a liquid Gallium alloy. PMID:26751444

Screening of liquids for thermocapillary bubble movement

NASA Technical Reports Server (NTRS)

Wilcox, W. R.; Subramanian, R. S.; Papazian, J. M.; Smith, H. D.; Mattox, D. M.

1979-01-01

Ground-based methods for pretesting qualitatively the thermocapillary movement of gas bubbles in a liquid to be used in space processing are discussed. Theoretical considerations are shown to require the use of a thin, enclosed, horizontal liquid film in order that the bubbles move faster than the bulk convection of the liquid, with insulating boundaries to prevent the onset of instabilities. Experimental realizations of horizontal cells in which to test the thermocapillary movement of bubbles in sheets of molten glass heated from below and organic melts in tubes heated from both ends are briefly described and the results of experiments are indicated.

Investigation of a Method to Reduce Cavitation in Diesel Engine Bearings

NASA Technical Reports Server (NTRS)

Keith, Theo G., Jr.; Honaker, Robert W.

1998-01-01

Sonoluminescence is the effect of producing light from sound and occurs when a gas bubble is trapped in a fluid filled cavity and is forced to collapse under a barrage of sound waves. Frenzel and Schultes discovered this phenomenon in 1934 while exposing acoustic waves to photographic plates. This effect was not well understood until 1988 when Crum and Gaitan discovered the necessary conditions for producing single bubble sonoluminescence in the laboratory. The luminescence is a result of the bubble violently collapsing from sound waves and this shares a close association with vibratory cavitation. Cavitation erosion is known to cause damage to rotational machinery when the collapse is near to surfaces due to the high pressures associated with bubble collapse. With these high pressures and temperatures there is a considerable amount of damage to the outside layer of a bearing, thereby, reducing its useful life. An experiment was constructed to generate sonoluminescence in the laboratory in order to obtain a greater understanding of this phenomenon and its association with bubble cavitation. Most of the research was done to investigate how to obtain single bubble sonoluminescence under different conditions and to determine how to detect it. Success in this has inspired several theories on how to use the methods for generating sonoluminescence to control cavitation in fluids under industrial conditions.

A monolithic mass tracking formulation for bubbles in incompressible flow

NASA Astrophysics Data System (ADS)

Aanjaneya, Mridul; Patkar, Saket; Fedkiw, Ronald

2013-08-01

We devise a novel method for treating bubbles in incompressible flow that relies on the conservative advection of bubble mass and an associated equation of state in order to determine pressure boundary conditions inside each bubble. We show that executing this algorithm in a traditional manner leads to stability issues similar to those seen for partitioned methods for solid-fluid coupling. Therefore, we reformulate the problem monolithically. This is accomplished by first proposing a new fully monolithic approach to coupling incompressible flow to fully nonlinear compressible flow including the effects of shocks and rarefactions, and then subsequently making a number of simplifying assumptions on the air flow removing not only the nonlinearities but also the spatial variations of both the density and the pressure. The resulting algorithm is quite robust, has been shown to converge to known solutions for test problems, and has been shown to be quite effective on more realistic problems including those with multiple bubbles, merging and pinching, etc. Notably, this approach departs from a standard two-phase incompressible flow model where the air flow preserves its volume despite potentially large forces and pressure differentials in the surrounding incompressible fluid that should change its volume. Our bubbles readily change volume according to an isothermal equation of state.

Point prevalence and incidence of Mycobacterium tuberculosis complex in captive elephants in the United States of America.

PubMed

Feldman, Melissa; Isaza, Ramiro; Prins, Cindy; Hernandez, Jorge

2013-01-01

Captive elephants infected with tuberculosis are implicated as an occupational source of zoonotic tuberculosis. However, accurate estimates of prevalence and incidence of elephant tuberculosis from well-defined captive populations are lacking in the literature. Studies published in recent years contain a wide range of prevalence estimates calculated from summary data. Incidence estimates of elephant tuberculosis in captive elephants are not available. This study estimated the annual point prevalence, annual incidence, cumulative incidence, and incidence density of tuberculosis in captive elephants within the USA during the past 52 years. We combined existing elephant census records from captive elephants in the USA with tuberculosis culture results obtained from trunk washes or at necropsy. This data set included 15 years where each elephant was screened annually. Between 1960 and 1996, the annual point prevalence of tuberculosis complex mycobacteria for both species was 0. From 1997 through 2011, the median point prevalence within the Asian elephant population was 5.1%, with a range from 0.3% to 6.7%. The incidence density was 9.7 cases/1000 elephant years (95% CI: 7.0-13.4). In contrast, the annual point prevalence during the same time period within the African elephant population remained 0 and the incidence density was 1.5 cases/1000 elephant years (95% CI: 0.7-4.0). The apparent increase in new cases noted after 1996 resulted from a combination of both index cases and the initiation of mandatory annual tuberculosis screening in 1997 for all the elephants. This study found lower annual point prevalence estimates than previously reported in the literature. These discrepancies in prevalence estimates are primarily due to differences in terminology and calculation methods. Using the same intensive testing regime, the incidence of tuberculosis differed significantly between Asian and African elephants. Accurate and species specific knowledge of prevalence and incidence will inform our efforts to mitigate occupational risks associated with captive elephants in the USA.

Grande Ronde Basin Chinook Salmon Captive Brood and Conventional Supplementation Programs, 2003 Annual Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffnagle, Timothy L.; Hair, Don; Carmichael, Richard W.

2004-07-01

BPA Fish and Wildlife Program Project Number 1998-01-001 provides funding for the Grande Ronde Basin Spring Chinook Salmon Captive Broodstock Program. This report satisfies the requirement that an annual report be submitted for FY 2003. The Grande Ronde Basin Spring Chinook Salmon Captive Broodstock Project is designed to rapidly increase numbers of salmon in stocks that are in imminent danger of extirpation. Parr are captured in Catherine Creek, upper Grande Ronde River and Lostine River and reared to adulthood in captivity. Upon maturation, these fish are spawned (within stocks) and their progeny reared to smoltification before being released into themore » natal stream of their parents. This program is co-managed by ODFW, National Marine Fisheries Service, Nez Perce Tribe and Confederated Tribes of the Umatilla Indian Reservation. This report covers activities conducted and provides data analyses for the Grande Ronde Spring Chinook Salmon Captive broodstock Program from 1 January--31 December 2003. Since the fiscal year ends in the middle of the spawning period, an annual report based on calendar year is more logical. This document is the FY 2003 annual report. Detailed information on historic and present population status, project background, goals and objectives, significance to regional programs and relationships to other programs, methods and previous results are available in the 1995-2002 Project Status Report (Hoffnagle et al 2003).« less

Bacterial populations and metabolites in the feces of free roaming and captive grizzly bears.

PubMed

Schwab, Clarissa; Cristescu, Bogdan; Boyce, Mark S; Stenhouse, Gordon B; Gänzle, Michael

2009-12-01

Gut physiology, host phylogeny, and diet determine the composition of the intestinal microbiota. Grizzly bears (Ursus arctos horribilis) belong to the Order Carnivora, yet feed on an omnivorous diet. The role of intestinal microflora in grizzly bear digestion has not been investigated. Microbiota and microbial activity were analysed from the feces of wild and captive grizzly bears. Bacterial composition was determined using culture-dependent and culture-independent methods. The feces of wild and captive grizzly bears contained log 9.1 +/- 0.5 and log 9.2 +/- 0.3 gene copies x g(-1), respectively. Facultative anaerobes Enterobacteriaceae and enterococci were dominant in wild bear feces. Among the strict anaerobes, the Bacteroides-Prevotella-Porphyromonas group was most prominent. Enterobacteriaceae were predominant in the feces of captive grizzly bears, at log 8.9 +/- 0.5 gene copies x g(-1). Strict anaerobes of the Bacteroides-Prevotella-Porphyromonas group and the Clostridium coccoides cluster were present at log 6.7 +/- 0.9 and log 6.8 +/- 0.8 gene copies x g(-1), respectively. The presence of lactate and short-chain fatty acids (SCFAs) verified microbial activity. Total SCFA content and composition was affected by diet. SCFA composition in the feces of captive grizzly bears resembled the SCFA composition of prey-consuming wild animals. A consistent data set was obtained that associated fecal microbiota and metabolites with the distinctive gut physiology and diet of grizzly bears.

Birth Origin Differentially Affects Depressive-Like Behaviours: Are Captive-Born Cynomolgus Monkeys More Vulnerable to Depression than Their Wild-Born Counterparts?

PubMed Central

Camus, Sandrine MJ.; Rochais, Céline; Blois-Heulin, Catherine; Li, Qin; Hausberger, Martine; Bezard, Erwan

2013-01-01

Background Adverse early-life experience might lead to the expression of abnormal behaviours in animals and the predisposition to psychiatric disorder (e.g. major depressive disorder) in Humans. Common breeding processes employ weaning and housing conditions different from what happens in the wild. Methods The present study, therefore, investigated whether birth origin impacts the possible existence of spontaneous atypical/abnormal behaviours displayed by 40 captive-born and 40 wild-born socially-housed cynomolgus macaques in farming conditions using an unbiased ethological scan-sampling analysis followed by multifactorial correspondence and hierarchical clustering analyses. Results We identified 10 distinct profiles (groups A to J) that significantly differed on several behaviours, body postures, body orientations, distances between individuals and locations in the cage. Data suggest that 4 captive-born and 1 wild-born animals (groups G and J) present depressive-like symptoms, unnatural early life events thereby increasing the risk of developing pathological symptoms. General differences were also highlighted between the captive- and wild-born populations, implying the expression of differential coping mechanisms in response to the same captive environment. Conclusions Birth origin thus impacts the development of atypical ethologically-defined behavioural profiles, reminiscent of certain depressive-like symptoms. The use of unbiased behavioural observations might allow the identification of animal models of human mental/behavioural disorders and their most appropriate control groups. PMID:23861787

Bubble Continuous Positive Airway Pressure Enhances Lung Volume and Gas Exchange in Preterm Lambs

PubMed Central

Pillow, J. Jane; Hillman, Noah; Moss, Timothy J. M.; Polglase, Graeme; Bold, Geoff; Beaumont, Chris; Ikegami, Machiko; Jobe, Alan H.

2007-01-01

Rationale: The technique used to provide continuous positive airway pressure (CPAP) to the newborn may influence lung function and breathing efficiency. Objectives: To compare differences in gas exchange physiology and lung injury resulting from treatment of respiratory distress with either bubble or constant pressure CPAP and to determine if the applied flow influences short-term outcomes. Methods: Lambs (133 d gestation; term is 150 d) born via cesarean section were weighed, intubated, and treated with CPAP for 3 hours. Two groups were treated with 8 L/minute applied flow using the bubble (n = 12) or the constant pressure (n = 12) technique. A third group (n = 10) received the bubble method with 12 L/minute bias flow. Measurements at study completion included arterial blood gases, oxygraphy, capnography, tidal flow, multiple breath washout, lung mechanics, static pressure–volume curves, and bronchoalveolar lavage fluid protein. Measurements and Main Results: Birth weight and arterial gas variables at 15 minutes were comparable. Flow (8 or 12 L/min) did not influence the 3-hour outcomes in the bubble group. Bubble technique was associated with a higher pH, PaO2, oxygen uptake, and area under the flow–volume curve, and a decreased alveolar protein, respiratory quotient, PaCO2, and ventilation inhomogeneity compared with the constant pressure group. Conclusions: Compared with constant pressure technique, bubble CPAP promotes enhanced airway patency during treatment of acute postnatal respiratory disease in preterm lambs and may offer protection against lung injury. PMID:17431223

Selecting the swimming mechanisms of colloidal particles: bubble propulsion versus self-diffusiophoresis.

PubMed

Wang, Sijia; Wu, Ning

2014-04-01

Bubble propulsion and self-diffusiophoresis are two common mechanisms that can drive autonomous motion of microparticles in hydrogen peroxide. Although microtubular particles, when coated with platinum in their interior concave surfaces, can propel due to the formation and release of bubbles from one end, the convex Janus particles usually do not generate any visible bubble. They move primarily due to the self-diffusiophoresis. Coincidentally, the platinum films on those particles were typically coated by physical evaporation. In this paper, we use a simple chemical deposition method to make platinum-polystyrene Janus dimers. Surprisingly, those particles are propelled by periodic growth and collapse of bubbles on the platinum-coated lobes. We find that both high catalytic activity and rough surface are necessary to change the propulsion mode from self-diffusiophoresis to bubble propulsion. Our Janus dimers, with combined geometric and interfacial anisotropy, also exhibit distinctive motions at the respective stages of bubble growth and collapse, which differ by 5-6 orders of magnitude in time. Our study not only provides insight into the link between self-diffusiophoresis and bubble propulsion but also reveals the intriguing impacts of the combined geometric and interfacial anisotropy on self-propulsion of particles.

Prospecting for zones of contaminated ground-water discharge to streams using bottom-sediment gas bubbles

USGS Publications Warehouse

Vroblesky, Don A.; Lorah, Michelle M.

1991-01-01

Decomposition of organic-rich bottom sediment in a tidal creek in Maryland results in production of gas bubbles in the bottom sediment during summer and fall. In areas where volatile organic contaminants discharge from ground water, through the bottom sediment, and into the creek, part of the volatile contamination diffuses into the gas bubbles and is released to the atmosphere by ebullition. Collection and analysis of gas bubbles for their volatile organic contaminant content indicate that relative concentrations of the volatile organic contaminants in the gas bubbles are substantially higher in areas where the same contaminants occur in the ground water that discharges to the streams. Analyses of the bubbles located an area of previously unknown ground-water contamination. The method developed for this study consisted of disturbing the bottom sediment to release gas bubbles, and then capturing the bubbles in a polyethylene bag at the water-column surface. The captured gas was transferred either into sealable polyethylene bags for immediate analysis with a photoionization detector or by syringe to glass tubes containing wires coated with an activated-carbon adsorbent. Relative concentrations were determined by mass spectral analysis for chloroform and trichloroethylene.

Modeling of single film bubble and numerical study of the plateau structure in foam system

NASA Astrophysics Data System (ADS)

Sun, Zhong-guo; Ni, Ni; Sun, Yi-jie; Xi, Guang

2018-02-01

The single-film bubble has a special geometry with a certain amount of gas shrouded by a thin layer of liquid film under the surface tension force both on the inside and outside surfaces of the bubble. Based on the mesh-less moving particle semi-implicit (MPS) method, a single-film double-gas-liquid-interface surface tension (SDST) model is established for the single-film bubble, which characteristically has totally two gas-liquid interfaces on both sides of the film. Within this framework, the conventional surface free energy surface tension model is improved by using a higher order potential energy equation between particles, and the modification results in higher accuracy and better symmetry properties. The complex interface movement in the oscillation process of the single-film bubble is numerically captured, as well as typical flow phenomena and deformation characteristics of the liquid film. In addition, the basic behaviors of the coalescence and connection process between two and even three single-film bubbles are studied, and the cases with bubbles of different sizes are also included. Furthermore, the classic plateau structure in the foam system is reproduced and numerically proved to be in the steady state for multi-bubble connections.

Bubble Combustion

NASA Technical Reports Server (NTRS)

Corrigan, Jackie

2004-01-01

A method of energy production that is capable of low pollutant emissions is fundamental to one of the four pillars of NASA s Aeronautics Blueprint: Revolutionary Vehicles. Bubble combustion, a new engine technology currently being developed at Glenn Research Center promises to provide low emissions combustion in support of NASA s vision under the Emissions Element because it generates power, while minimizing the production of carbon dioxide (CO2) and nitrous oxides (NOx), both known to be Greenhouse gases. and allows the use of alternative fuels such as corn oil, low-grade fuels, and even used motor oil. Bubble combustion is analogous to the inverse of spray combustion: the difference between bubble and spray combustion is that spray combustion is spraying a liquid in to a gas to form droplets, whereas bubble combustion involves injecting a gas into a liquid to form gaseous bubbles. In bubble combustion, the process for the ignition of the bubbles takes place on a time scale of less than a nanosecond and begins with acoustic waves perturbing each bubble. This perturbation causes the local pressure to drop below the vapor pressure of the liquid thus producing cavitation in which the bubble diameter grows, and upon reversal of the oscillating pressure field, the bubble then collapses rapidly with the aid of the high surface tension forces acting on the wall of the bubble. The rapid and violent collapse causes the temperatures inside the bubbles to soar as a result of adiabatic heating. As the temperatures rise, the gaseous contents of the bubble ignite with the bubble itself serving as its own combustion chamber. After ignition, this is the time in the bubble s life cycle where power is generated, and CO2, and NOx among other species, are produced. However, the pollutants CO2 and NOx are absorbed into the surrounding liquid. The importance of bubble combustion is that it generates power using a simple and compact device. We conducted a parametric study using CAVCHEM, a computational model developed at Glenn, that simulates the cavitational collapse of a single bubble in a liquid (water) and the subsequent combustion of the gaseous contents inside the bubble. The model solves the time-dependent, compressible Navier-Stokes equations in one-dimension with finite-rate chemical kinetics using the CHEMKIN package. Specifically, parameters such as frequency, pressure, bubble radius, and the equivalence ratio were varied while examining their effect on the maximum temperature, radius, and chemical species. These studies indicate that the radius of the bubble is perhaps the most critical parameter governing bubble combustion dynamics and its efficiency. Based on the results of the parametric studies, we plan on conducting experiments to study the effect of ultrasonic perturbations on the bubble generation process with respect to the bubble radius and size distribution.

Predicting financial market crashes using ghost singularities.

PubMed

Smug, Damian; Ashwin, Peter; Sornette, Didier

2018-01-01

We analyse the behaviour of a non-linear model of coupled stock and bond prices exhibiting periodically collapsing bubbles. By using the formalism of dynamical system theory, we explain what drives the bubbles and how foreshocks or aftershocks are generated. A dynamical phase space representation of that system coupled with standard multiplicative noise rationalises the log-periodic power law singularity pattern documented in many historical financial bubbles. The notion of 'ghosts of finite-time singularities' is introduced and used to estimate the end of an evolving bubble, using finite-time singularities of an approximate normal form near the bifurcation point. We test the forecasting skill of this method on different stochastic price realisations and compare with Monte Carlo simulations of the full system. Remarkably, the approximate normal form is significantly more precise and less biased. Moreover, the method of ghosts of singularities is less sensitive to the noise realisation, thus providing more robust forecasts.

Predicting financial market crashes using ghost singularities

PubMed Central

2018-01-01

We analyse the behaviour of a non-linear model of coupled stock and bond prices exhibiting periodically collapsing bubbles. By using the formalism of dynamical system theory, we explain what drives the bubbles and how foreshocks or aftershocks are generated. A dynamical phase space representation of that system coupled with standard multiplicative noise rationalises the log-periodic power law singularity pattern documented in many historical financial bubbles. The notion of ‘ghosts of finite-time singularities’ is introduced and used to estimate the end of an evolving bubble, using finite-time singularities of an approximate normal form near the bifurcation point. We test the forecasting skill of this method on different stochastic price realisations and compare with Monte Carlo simulations of the full system. Remarkably, the approximate normal form is significantly more precise and less biased. Moreover, the method of ghosts of singularities is less sensitive to the noise realisation, thus providing more robust forecasts. PMID:29596485

Bubbles in solvent microextraction: the influence of intentionally introduced bubbles on extraction efficiency.

PubMed

Williams, D Bradley G; George, Mosotho J; Meyer, Riaan; Marjanovic, Ljiljana

2011-09-01

Significant improvements to microdrop extractions of triazine pesticides are realized by the intentional incorporation of an air bubble into the solvent microdroplet used in this microextraction technique. The increase is attributed partly to greater droplet surface area resulting from the air bubble being incorporated into the solvent droplet as opposed to it sitting thereon and partly to thin film phenomena. The method is useful at nanogram/liter levels (LOD 0.002-0.012 μg/L, LOQ 0.007-0.039 μg/L), is precise (7-12% at 10 μg/L concentration level), and is validated against certified reference materials containing 0.5 and 5.0 μg/L analyte. It tolerates water and fruit juice as matrixes without serious matrix effects. This new development brings a simple, inexpensive, and efficient preconcentration technique to bear which rivals solid phase microextraction methods.

Method and means for producing solid evacuated microspheres of hydrogen

DOEpatents

Turnbull, Robert J.; Foster, Christopher A.; Hendricks, Charles D.

1976-01-01

A method is provided for producing solid, evacuated microspheres comprised of hydrogen. The spheres are produced by forming a jet of liquid hydrogen and exciting mechanical waves on the jet of appropriate frequency so that the jet breaks up into drops with a bubble formed in each drop by cavitation. The drops are exposed to a pressure less than the vapor pressure of the liquid hydrogen so that the bubble which is formed within each drop expands. The drops which contain bubbles are exposed to an environment having a pressure just below the triple point of liquid hydrogen and they thereby freeze giving solid, evacuated spheres of hydrogen.

Experimental microbubble generation by sudden pressure drop and fluidics

NASA Astrophysics Data System (ADS)

Franco Gutierrez, Fernando; Figueroa Espinoza, Bernardo; Aguilar Corona, Alicia; Vargas Correa, Jesus; Solorio Diaz, Gildardo

2014-11-01

Mass and heat transfer, as well as chemical species in bubbly flow are of importance in environmental and industrial applications. Microbubbles are well suited to these applications due to the large interface contact area and residence time. The objective of this investigation is to build devices to produce microbubbles using two methods: pressure differences and fluidics. Some characteristics, advantages and drawbacks of both methods are briefly discussed, as well as the characterization of the bubbly suspensions in terms of parameters such as the pressure jump and bubble equivalent diameter distribution. The authors acknowledge the support of Consejo Nacional de Ciencia y Tecnología.

Numerical Modeling of the Photothermal Processing for Bubble Forming around Nanowire in a Liquid

PubMed Central

Chaari, Anis; Giraud-Moreau, Laurence

2014-01-01

An accurate computation of the temperature is an important factor in determining the shape of a bubble around a nanowire immersed in a liquid. The study of the physical phenomenon consists in solving a photothermic coupled problem between light and nanowire. The numerical multiphysic model is used to study the variations of the temperature and the shape of the created bubble by illumination of the nanowire. The optimization process, including an adaptive remeshing scheme, is used to solve the problem through a finite element method. The study of the shape evolution of the bubble is made taking into account the physical and geometrical parameters of the nanowire. The relation between the sizes and shapes of the bubble and nanowire is deduced. PMID:24795538

Air and blood fluid dynamics: at the interface between engineering and medicine

NASA Astrophysics Data System (ADS)

Pollard, A.; Secretain, F.; Milne, B.

2014-08-01

The flows in the human upper airway and human heart during open heart surgery are considered. Beginning with idealized models of the human upper airway, current methods to extract realistic airway geometries using a novel implementation of optical coherent tomography modality are introduced. Complementary direct numerical simulations are considered that will assist in pre-surgery planning for obstructive sleep apnea. Cardiac air bubbles often arise during open heart surgery. These bubbles are potential emboli that can cause neurological impairment and even death. An experimental programme is outlined that uses acoustic sound to instil bubble surface oscillations that result in bubble breakup. A novel algorithm is introduced that enables a surgical team to obtain real-time in-vivo bubble data to aid cardiac de-airation procedures.

Microstreaming from Sessile Semicylindrical Bubbles

NASA Astrophysics Data System (ADS)

Hilgenfeldt, Sascha; Rallabandi, Bhargav; Guo, Lin; Wang, Cheng

2014-03-01

Powerful steady streaming flows result from the ultrasonic driving of microbubbles, in particular when these bubbles have semicylindrical cross section and are positioned in contact with a microfluidic channel wall. We have used this streaming in experiment to develop novel methods for trapping and sorting of microparticles by size, as well as for micromixing. Theoretically, we arrive at an analytical description of the streaming flow field through an asymptotic computation that, for the first time, reconciles the boundary layers around the bubble and along the substrate wall, and also takes into account the oscillation modes of the bubble. This approach gives insight into changes in the streaming pattern with bubble size and driving frequency, including a reversal of the flow direction at high frequencies with potentially useful applications. Present address: Mechanical and Aerospace Engineering, Missouri S &T.

Effects of long-term captivity on thermoregulation, metabolism and ventilation of the southern brown bandicoot (Marsupialia: Peramelidae).

PubMed

Larcombe, Alexander N; Withers, Philip C

2007-02-01

Thermoneutral metabolic and ventilatory parameters were measured every 3 months over 2 years for southern brown bandicoots held in captivity, and from a nearby reserve. Captive bandicoots were 130 g (9.9%) heavier than wild bandicoots. Long-term captivity had no effect on body temperature, basal metabolic rate (oxygen consumption), thermal conductance or respiratory ventilation, but there was an effect on carbon dioxide production, respiratory exchange ratio and total evaporative water loss (values were between 15 and 25% higher for captive than for wild bandicoots). Diet may be influencing these aspects of captive bandicoot physiology; the diet of captive bandicoots would be considerably different to that of wild bandicoots. Water availability seems to have a minimal effect. This study has important implications regarding physiological measurement for captive and wild mammals. For bandicoots at least, captive animals are equivalent to wild animals for some physiological parameters at thermoneutrality (body temperature, resting metabolic rate and thermal conductance), but not others.

Collective dissolution of microbubbles

NASA Astrophysics Data System (ADS)

Michelin, Sébastien; Guérin, Etienne; Lauga, Eric

2018-04-01

A microscopic bubble of soluble gas always dissolves in finite time in an undersaturated fluid. This diffusive process is driven by the difference between the gas concentration near the bubble, whose value is governed by the internal pressure through Henry's law, and the concentration in the far field. The presence of neighboring bubbles can significantly slow down this process by increasing the effective background concentration and reducing the diffusing flux of dissolved gas experienced by each bubble. We develop theoretical modeling of such diffusive shielding process in the case of small microbubbles whose internal pressure is dominated by Laplace pressure. We first use an exact semianalytical solution to capture the case of two bubbles and analyze in detail the shielding effect as a function of the distance between the bubbles and their size ratio. While we also solve exactly for the Stokes flow around the bubble, we show that hydrodynamic effects are mostly negligible except in the case of almost-touching bubbles. In order to tackle the case of multiple bubbles, we then derive and validate two analytical approximate yet generic frameworks, first using the method of reflections and then by proposing a self-consistent continuum description. Using both modeling frameworks, we examine the dissolution of regular one-, two-, and three-dimensional bubble lattices. Bubbles located at the edge of the lattices dissolve first, while innermost bubbles benefit from the diffusive shielding effect, leading to the inward propagation of a dissolution front within the lattice. We show that diffusive shielding leads to severalfold increases in the dissolution time, which grows logarithmically with the number of bubbles in one-dimensional lattices and algebraically in two and three dimensions, scaling respectively as its square root and 2 /3 power. We further illustrate the sensitivity of the dissolution patterns to initial fluctuations in bubble size or arrangement in the case of large and dense lattices, as well as nonintuitive oscillatory effects.

Mass transport phenomena between bubbles and dissolved gases in liquids under reduced gravity conditions

NASA Technical Reports Server (NTRS)

Dewitt, Kenneth J.; Brockwell, Jonathan L.; Yung, Chain-Nan; Chai, An-Ti; Mcquillen, John B.; Sotos, Raymond G.; Neumann, Eric S.

1988-01-01

The experimental and analytical work that was done to establish justification and feasibility for a shuttle middeck experiment involving mass transfer between a gas bubble and a liquid is described. The experiment involves the observation and measurement of the dissolution of an isolated immobile gas bubble of specified size and composition in a thermostatted solvent liquid of known concentration in the reduced gravity environment of earth orbit. Methods to generate and deploy the bubble were successful both in normal gravity using mutually buoyant fluids and under reduced gravity conditions in the NASA Lear Jet. Initialization of the experiment with a bubble of a prescribed size and composition in a liquid of known concentration was accomplished using the concept of unstable equilibrium. Subsequent bubble dissolution or growth is obtained by a step increase or decrease in the liquid pressure. A numerical model was developed which simulates the bubble dynamics and can be used to determine molecular parameters by comparison with the experimental data. The primary objective of the experiment is the elimination of convective effects that occur in normal gravity.

Development of an optical microscopy system for automated bubble cloud analysis.

PubMed

Wesley, Daniel J; Brittle, Stuart A; Toolan, Daniel T W

2016-08-01

Recently, the number of uses of bubbles has begun to increase dramatically, with medicine, biofuel production, and wastewater treatment just some of the industries taking advantage of bubble properties, such as high mass transfer. As a result, more and more focus is being placed on the understanding and control of bubble formation processes and there are currently numerous techniques utilized to facilitate this understanding. Acoustic bubble sizing (ABS) and laser scattering techniques are able to provide information regarding bubble size and size distribution with minimal data processing, a major advantage over current optical-based direct imaging approaches. This paper demonstrates how direct bubble-imaging methods can be improved upon to yield high levels of automation and thus data comparable to ABS and laser scattering. We also discuss the added benefits of the direct imaging approaches and how it is possible to obtain considerable additional information above and beyond that which ABS and laser scattering can supply. This work could easily be exploited by both industrial-scale operations and small-scale laboratory studies, as this straightforward and cost-effective approach is highly transferrable and intuitive to use.

Three-dimensional features on oscillating microbubbles streaming flows

NASA Astrophysics Data System (ADS)

Rossi, Massimiliano; Marin, Alvaro G.; Wang, Cheng; Hilgenfeldt, Sascha; Kähler, Christian J.

2013-11-01

Ultrasound-driven oscillating micro-bubbles have been used as active actuators in microfluidic devices to perform manifold tasks such as mixing, sorting and manipulation of microparticles. A common configuration consists in side-bubbles, created by trapping air pockets in blind channels perpendicular to the main channel direction. This configuration results in bubbles with a semi-cylindrical shape that creates a streaming flow generally considered quasi two-dimensional. However, recent experiments performed with three-dimensional velocimetry methods have shown how microparticles can present significant three-dimensional trajectories, especially in regions close to the bubble interface. Several reasons will be discussed such as boundary effects of the bottom/top wall, deformation of the bubble interface leading to more complex vibrational modes, or bubble-particle interactions. In the present investigation, precise measurements of particle trajectories close to the bubble interface will be performed by means of 3D Astigmatic Particle Tracking Velocimetry. The results will allow us to characterize quantitatively the three-dimensional features of the streaming flow and to estimate its implications in practical applications as particle trapping, sorting or mixing.

Coarsening of firefighting foams containing fluorinated hydrocarbon surfactants

NASA Astrophysics Data System (ADS)

Kennedy, Matthew J.; Dougherty, John A.; Otto, Nicholas; Conroy, Michael W.; Williams, Bradley A.; Ananth, Ramagopal; Fleming, James W.

2013-03-01

Diffusion of gas between bubbles in foam causes growth of large bubbles at the expense of small bubbles and leads to increasing mean bubble size with time thereby affecting drainage. Experimental data shows that the effective diffusivity of nitrogen gas in aqueous film forming foam (AFFF), which is widely used in firefighting against burning liquids, is several times smaller than in 1% sodium dodecyl sulfate (SDS) foam based on time-series photographs of bubble size and weighing scale recordings of liquid drainage. Differences in foam structure arising from foam production might contribute to the apparent difference in the rates of coarsening. AFFF solution produces wetter foam with initially smaller bubbles than SDS solution due in part to the lower gas-liquid surface tension provided by the fluorosurfactants present in AFFF. Present method of foam production generates microbubble foam by high-speed co-injection of surfactant solution and gas into a tube of 3-mm diameter. These results contribute to our growing understanding of the coupling between foam liquid fraction, bubble size, surfactant chemistry, and coarsening. NRC Resident Research Associate at NRL

Physical cleaning by bubbly streaming flow in an ultrasound field

NASA Astrophysics Data System (ADS)

Yamashita, Tatsuya; Ando, Keita

2017-11-01

Low-intensity ultrasonic cleaning with gas-supersaturated water is a promising method of physical cleaning without erosion; we are able to trigger cavitation bubble nucleation by weak ultrasound under gas supersaturation and thus clean material surfaces by mild bubble dynamics. Here, we perform particle image velocimetry (PIV) measurement of liquid flow and cavitation bubble translation in an ultrasonic cleaning bath driven at 28 kHz and then relate it to cleaning tests using glass slides at which silica particles are attached. The ultrasound pressure amplitude at the cleaning spot is set at 1.4 atm. We select the supersaturation level of dissolved oxygen (DO) as a parameter and control it by oxygen microbubble aeration. It follows from the PIV measurement that the liquid flow is enhanced by the cavitation bubble translation driven by acoustic radiation force; this trend becomes clearer when the bubbles appear more densely as the DO supersaturation increases. In the cleaning tests, the cleaned areas appear as straight streaks. This suggests that physical cleaning is achieved mainly by cavitation bubbles that translate in ultrasound fields.

Nanoparticle coated optical fibers for single microbubble generation

NASA Astrophysics Data System (ADS)

Pimentel-Domínguez, Reinher; Hernández-Cordero, Juan

2011-09-01

The study of bubbles and bubbly flows is important in various fields such as physics, chemistry, medicine, geophysics, and even the food industry. A wide variety of mechanical and acoustic techniques have been reported for bubble generation. Although a single bubble may be generated with these techniques, controlling the size and the mean lifetime of the bubble remains a difficult task. Most of the optical methods for generation of microbubbles involve high-power pulsed laser sources focused in absorbing media such as liquids or particle solutions. With these techniques, single micron-sized bubbles can be generated with typical mean lifetimes ranging from nano to microseconds. The main problem with these bubbles is their abrupt implosion: this produces a shock wave that can potentially produce damages on the surroundings. These effects have to be carefully controlled in biological applications and in laser surgery, but thus far, not many options are available to effectively control micron-size bubble growth. In this paper, we present a new technique to generate microbubbles in non-absorbing liquids. In contrast to previous reports, the proposed technique uses low-power and a CW radiation from a laser diode. The laser light is guided through an optical fiber whose output end has been coated with nanostructures. Upon immersing the tip of the fiber in ethanol or water, micron-size bubbles can be readily generated. With this technique, bubble growth can be controlled through adjustments on the laser power. We have obtained micron-sized bubbles with mean lifetimes in the range of seconds. Furthermore, the generated bubbles do not implode, as verified with a high-speed camera and flow visualization techniques.

Modeling and Measurements of Multiphase Flow and Bubble Entrapment in Steel Continuous Casting

NASA Astrophysics Data System (ADS)

Jin, Kai; Thomas, Brian G.; Ruan, Xiaoming

2016-02-01

In steel continuous casting, argon gas is usually injected to prevent clogging, but the bubbles also affect the flow pattern, and may become entrapped to form defects in the final product. To investigate this behavior, plant measurements were conducted, and a computational model was applied to simulate turbulent flow of the molten steel and the transport and capture of argon gas bubbles into the solidifying shell in a continuous slab caster. First, the flow field was solved with an Eulerian k- ɛ model of the steel, which was two-way coupled with a Lagrangian model of the large bubbles using a discrete random walk method to simulate their turbulent dispersion. The flow predicted on the top surface agreed well with nailboard measurements and indicated strong cross flow caused by biased flow of Ar gas due to the slide-gate orientation. Then, the trajectories and capture of over two million bubbles (25 μm to 5 mm diameter range) were simulated using two different capture criteria (simple and advanced). Results with the advanced capture criterion agreed well with measurements of the number, locations, and sizes of captured bubbles, especially for larger bubbles. The relative capture fraction of 0.3 pct was close to the measured 0.4 pct for 1 mm bubbles and occurred mainly near the top surface. About 85 pct of smaller bubbles were captured, mostly deeper down in the caster. Due to the biased flow, more bubbles were captured on the inner radius, especially near the nozzle. On the outer radius, more bubbles were captured near to narrow face. The model presented here is an efficient tool to study the capture of bubbles and inclusion particles in solidification processes.

Population recovery of the Whooping Crane with emphasis on reintroduction efforts: Past and future

USGS Publications Warehouse

Ellis, D.H.; Lewis, J.C.; Gee, G.F.; Smith, D.G.

1992-01-01

The U.S. Fish and Wildlife Service (USFWS) began building a captive whooping crane (Grus americana) colony at Patuxent Wildlife Research Center (Patuxent), Maryland, in 1966. From 1976 to 1984, 73 eggs from this colony and 216 eggs from Wood Buffalo National Park (Wood Buffalo), Canada, nests were placed in sandhill crane (G. canadensis) nests at Grays Lake National Wildlife Refuge (Grays Lake), Idaho, the site of the first whooping crane reintroduction attempt. Although 84 chicks fledged from the 289 eggs, the egg transfer program has been discontinued because of inordinately high mortality (only ca. 13 birds remain in the wild in 1991) and lack of breeding in survivors. In recent decades new methods have emerged for introducing captive-produced offspring to the wild. Surrogate studies with sandhill cranes, particularly the endangered Mississippi sandhill cranes (G. c. pulla), have shown that young cranes, raised either by captive, conspecific foster parents, or by costumed humans and in close association with live cranes and lifelike crane taxidermic dummies, have high post-release survival rates. These techniques will likely be used in future whooping crane reintroduction programs. Current recovery objectives for the whooping crane include expansion of the 2 captive colonies, establishment of a third captive colony in Canada, and reintroduction of 2 additional wild populations. The Kissimmee Prairie in central Florida has been selected for the next release experiment. Evaluation of this site began in 1984, and risk assessment is expected to begin in 1992 with the transfer and monitoring of a group of captive-reared, juvenile whooping cranes. These 'tests of the environment' will, if results are favorable, be followed by a full-scale reintroduction effort of at least 20 birds/year beginning in 1994 or 1995.

Acoustic observations of gas bubble streams in the NW Black Sea as a method for estimation of gas flux from vent sites

NASA Astrophysics Data System (ADS)

Artemov, Yu. G.

2003-04-01

Relatively recent discovery of the natural CH_4 gas seepage from the sea bed had action upon the philosophy of CH_4 contribution to global budgets. So far as numerous gas vent sites are known, an acceptable method for released gas quantification is required. In particular, the questions should be answered as follows: 1) how much amount of gas comes into the water column due to a certain bubble stream, 2) how much amount of gas comes into the water column due to a certain seepage area of the see floor, 3) how much amount of gas diffuses into the water and how much gas phase enters the atmosphere. Echo-sounder is the habitual equipment for detecting gas plumes (flares) in the water column. To provide observations of gas seeps with bubbles tracking, single target and volume backscattering strength measurements, we use installed on board the R/V "Professor Vodyanitskiy" dual frequency (38 and 120 kHz) split-beam scientific echo-sounder SIMRAD EK-500. Dedicated software is developed to extract from the raw echo data and to handle the definite information for analyses of gas bubble streams features. This improved hydroacoustic techniques allows to determine gas bubbles size spectrum at different depths through the water column as well as rise velocity of bubbles of different sizes. For instance, bubble of 4.5 mm diameter has rising speed of 25.8 cm/sec at 105 m depth, while bubble of 1.7 mm diameter has rising speed of 16.3 cm/sec at 32 m depth. Using volume backscattering measurements in addition, it is possible to evaluate flux of the gas phase produced by methane bubble streams and to learn of its fate in the water column. Ranking of various gas plumes by flux rate value is available also. In this presentation results of acoustic observations at the shallow NW Black Sea seepage area are given.

Imposing the free-slip condition with a continuous forcing immersed boundary method

NASA Astrophysics Data System (ADS)

Kempe, Tobias; Lennartz, Matthias; Schwarz, Stephan; Fröhlich, Jochen

2015-02-01

The numerical simulation of spherical and ellipsoidal bubbles in purified fluids requires the imposition of the free-slip boundary condition at the bubble surface. This paper describes a numerical method for the implementation of free-slip boundary conditions in the context of immersed boundary methods. In contrast to other numerical approaches for multiphase flows, the realization is not straightforward. The reason is that the immersed boundary method treats the liquid as well as the gas phase as a field of constant density and viscosity with a fictitious fluid inside the bubble. The motion of the disperse phase is computed explicitly by solving the momentum balance for each of its elements and is coupled to the continuous phase via additional source terms in the Navier-Stokes equations. The paper starts with illustrating that an ad hoc method is unsuccessful. On this basis, a new method is proposed employing appropriate direct forcing at the bubble surface. A central finding is that with common ratios between the step size of the grid and the bubble diameter, curvature terms need to be accounted for to obtain satisfactory results. The new method is first developed for spherical objects and then extended to generally curved interfaces. This is done by introducing a local coordinate system which approximates the surface in the vicinity of a Lagrangian marker with the help of the two principal curvatures of the surface at this point. The numerical scheme is then validated for spherical and ellipsoidal objects with or without prescribed constant angular velocity. It is shown that the proposed method achieves similar convergence behavior as the method for no-slip boundaries. The results are compared to analytical solutions for creeping flow around a sphere and to numerical reference data obtained on a body-fitted grid. The numerical tests confirm the excellent performance of the proposed method.

Bubble size statistics during reionization from 21-cm tomography

NASA Astrophysics Data System (ADS)

Giri, Sambit K.; Mellema, Garrelt; Dixon, Keri L.; Iliev, Ilian T.

2018-01-01

The upcoming SKA1-Low radio interferometer will be sensitive enough to produce tomographic imaging data of the redshifted 21-cm signal from the Epoch of Reionization. Due to the non-Gaussian distribution of the signal, a power spectrum analysis alone will not provide a complete description of its properties. Here, we consider an additional metric which could be derived from tomographic imaging data, namely the bubble size distribution of ionized regions. We study three methods that have previously been used to characterize bubble size distributions in simulation data for the hydrogen ionization fraction - the spherical-average (SPA), mean-free-path (MFP) and friends-of-friends (FOF) methods - and apply them to simulated 21-cm data cubes. Our simulated data cubes have the (sensitivity-dictated) resolution expected for the SKA1-Low reionization experiment and we study the impact of both the light-cone (LC) and redshift space distortion (RSD) effects. To identify ionized regions in the 21-cm data we introduce a new, self-adjusting thresholding approach based on the K-Means algorithm. We find that the fraction of ionized cells identified in this way consistently falls below the mean volume-averaged ionized fraction. From a comparison of the three bubble size methods, we conclude that all three methods are useful, but that the MFP method performs best in terms of tracking the progress of reionization and separating different reionization scenarios. The LC effect is found to affect data spanning more than about 10 MHz in frequency (Δz ∼ 0.5). We find that RSDs only marginally affect the bubble size distributions.

Observations of captive Rocky Mountain mule deer behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halford, D.K.; Arthur, W.J. III; Alldredge, A.W.

1987-01-31

Observations were made near Fort Collins, Colorado on the behavior of a captive herd of Rocky Mountain mule deer (Odocoileus hemionus hemionus). Comparisons in general behavior patterns were made between captive and wild deer. Similar behavior was exhibited by captive and wild deer. Captive deer (as well as other species) may be useful for study of certain behavioral aspects of their wild counterparts.

Exposure of the endangered golden monkey (Rhinopithecus roxellana) to heavy metals: a comparison of wild and captive animals.

PubMed

Liu, Qiang; Chen, Yi-Ping; Maltby, Lorraine; Ma, Qing-Yi

2015-05-01

Golden monkeys are endemic to China and of high conservation concern. Conservation strategies include captive breeding, but the success of captive breeding programs may be being compromised by environmental pollution. Heavy metal exposure of wild and captive golden monkeys living in the Qinling Mountains was assessed by measuring fecal metal concentrations (As, Cd, Cr, Co, Cu, Mn, Hg, Ni, Pb, and Zn). Captive monkeys were exposed to higher concentrations of As, Hg, Pb, and Cr than monkeys living in the wild, while high background levels of Mn led to high exposure of wild monkeys. Seasonal variations in metal exposures were detected for both wild and captive monkeys; possible reasons being seasonal changes in either diet (wild monkeys) or metal content of food (captive monkeys). Coal combustion, waste incineration, and traffic-related activities were identified as possible sources of heavy metals exposure for captive animals. Efforts to conserve this endangered primate are potentially compromised by metal pollutants derived from increasing anthropogenic activities. Providing captive animals with uncontaminated food and relocating captive breeding centers away from sources of pollution will reduce pollutant exposure; but ultimately, there is a need to improve environmental quality by controlling pollutants at source.

Does the stress response predict the ability of wild birds to adjust to short-term captivity? A study of the rock pigeon (Columbia livia)

PubMed Central

Parenteau, Charline; Trouvé, Colette; Angelier, Nicole

2016-01-01

Although the transfer of wild animals to captivity is crucial for conservation purposes, this process is often challenging because some species or individuals do not adjust well to captive conditions. Chronic stress has been identified as a major concern for animals held on long-term captivity. Surprisingly, the first hours or days of captivity have been relatively overlooked. However, they are certainly very stressful, because individuals are being transferred to a totally novel and confined environment. To ensure the success of conservation programmes, it appears crucial to better understand the proximate causes of interspecific and interindividual variability in the sensitivity to these first hours of captivity. In that respect, the study of stress hormones is relevant, because the hormonal stress response may help to assess whether specific individuals or species adjust, or not, to such captive conditions (‘the stress response-adjustment to captivity hypothesis’). We tested this hypothesis in rock pigeons by measuring their corticosterone stress response and their ability to adjust to short-term captivity (body mass loss and circulating corticosterone levels after a day of captivity). We showed that an increased corticosterone stress response is associated with a lower ability to adjust to short-term captivity (i.e. higher body mass loss and circulating corticosterone levels). Our study suggests, therefore, that a low physiological sensitivity to stress may be beneficial for adjusting to captivity. Future studies should now explore whether the stress response can be useful to predict the ability of individuals from different populations or species to not only adjust to short-term but also long-term captivity. PMID:28083117

Does the stress response predict the ability of wild birds to adjust to short-term captivity? A study of the rock pigeon (Columbia livia).

PubMed

Angelier, Frédéric; Parenteau, Charline; Trouvé, Colette; Angelier, Nicole

2016-12-01

Although the transfer of wild animals to captivity is crucial for conservation purposes, this process is often challenging because some species or individuals do not adjust well to captive conditions. Chronic stress has been identified as a major concern for animals held on long-term captivity. Surprisingly, the first hours or days of captivity have been relatively overlooked. However, they are certainly very stressful, because individuals are being transferred to a totally novel and confined environment. To ensure the success of conservation programmes, it appears crucial to better understand the proximate causes of interspecific and interindividual variability in the sensitivity to these first hours of captivity. In that respect, the study of stress hormones is relevant, because the hormonal stress response may help to assess whether specific individuals or species adjust, or not, to such captive conditions ('the stress response-adjustment to captivity hypothesis'). We tested this hypothesis in rock pigeons by measuring their corticosterone stress response and their ability to adjust to short-term captivity (body mass loss and circulating corticosterone levels after a day of captivity). We showed that an increased corticosterone stress response is associated with a lower ability to adjust to short-term captivity (i.e. higher body mass loss and circulating corticosterone levels). Our study suggests, therefore, that a low physiological sensitivity to stress may be beneficial for adjusting to captivity. Future studies should now explore whether the stress response can be useful to predict the ability of individuals from different populations or species to not only adjust to short-term but also long-term captivity.

Displacement of particles in microfluidics by laser-generated tandem bubbles

NASA Astrophysics Data System (ADS)

Lautz, Jaclyn; Sankin, Georgy; Yuan, Fang; Zhong, Pei

2010-11-01

The dynamic interaction between laser-generated tandem bubble and individual polystyrene particles of 2 and 10 μm in diameter is studied in a microfluidic channel (25 μm height) by high-speed imaging and particle image velocimetry. The asymmetric collapse of the tandem bubble produces a pair of microjets and associated long-lasting vortices that can propel a single particle to a maximum velocity of 1.4 m/s in 30 μs after the bubble collapse with a resultant directional displacement up to 60 μm in 150 μs. This method may be useful for high-throughput cell sorting in microfluidic devices.

Sterilization of microorganisms by the supercritical carbon dioxide micro-bubble method.

PubMed

Ishikawa, H; Shimoda, M; Shiratsuchi, H; Osajima, Y

1995-10-01

Lactobacillus brevis and Saccharomyces cerevisiae were completely sterilized by the supercritical (SC) CO2 micro-bubble method. Gaseous (G) and liquid (LQ) CO2 were used in a similar manner to compare the sterilizing effect. Among the three treatments, the microorganisms were only effectively sterilized by the SC CO2 treatment at 25 MPa and 35 degrees C.

Redfish Lake Sockeye Salmon Captive Broodstock Rearing and Research, Annual Report 2001-2002.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frost, Deborah; McAuley, W.; Maynard, Desmond

2003-04-01

The National Marine Fisheries Service (NMFS) Northwest Fisheries Science Center, in cooperation with the Idaho Department of Fish and Game and the Bonneville Power Administration, has established captive broodstock programs to aid recovery of Snake River sockeye salmon (Oncorhynchus nerka) listed as endangered under the U.S. Endangered Species Act (ESA). Captive broodstock and captive rearing programs are a form of artificial propagation that are emerging as an important component of restoration efforts for ESA-listed salmon populations that are at critically low numbers. Captive broodstocks, reared in captivity for the entire life cycle, couple the salmon's high fecundity with potentially highmore » survival in protective culture to produce large numbers of juveniles in a single generation for supplementation of natural populations. The captive broodstocks discussed in this report were intended to protect the last known remnants of sockeye salmon that return to Redfish Lake in the Sawtooth Basin of Idaho at the headwaters of the Salmon River. This report addresses NMFS activities from 1 September 2001 to 31 August 2002 on the Redfish Lake sockeye salmon captive broodstock and captive rearing program. NMFS currently has broodstocks in culture from year classes 1997, 1998, 1999, 2000, and 2001 in both the captive breeding and captive rearing programs. Offspring from these programs are being returned to Idaho to aid recovery efforts for the species.« less

A computational model of microbubble transport through a blood-filled vessel bifurcation

NASA Astrophysics Data System (ADS)

Calderon, Andres

2005-11-01

We are developing a novel gas embolotherapy technique to occlude blood vessels and starve tumors using gas bubbles that are produced by the acoustic vaporization of liquid perfluorocarbon droplets. The droplets are small enough to pass through the microcirculation, but the subsequent bubbles are large enough to lodge in vessels. The uniformity of tumor infarction depends on the transport the blood-borne bubbles before they stick. We examine the transport of a semi-infinite bubble through a single bifurcation in a liquid-filled two-dimensional channel. The flow is governed by the conservation of fluid mass and momentum equations. Reynolds numbers in the microcirculation are small, and we solve the governing equations using the boundary element method. The effect of gravity on bubble splitting is investigated and results are compared with our previous bench top experiments and to a quasi-steady one-dimensional analysis. The effects of daughter tube outlet pressures and bifurcation geometry are also considered. The findings suggest that slow moving bubbles will favor the upper branch of the bifurcation, but that increasing the bubble speed leads to more even splitting. It is also found that some bifurcation geometries and flow conditions result in severe thinning of the liquid film separating the bubble from the wall, suggesting the possibility bubble-wall contact. This work is supported by NSF grant BES-0301278 and NIH grant EB003541.

Mechanisms and methods for biofouling prevention via aeration

NASA Astrophysics Data System (ADS)

Dickenson, Natasha; Henoch, Charles; Belden, Jesse

2013-11-01

Biofouling is a major problem for the Navy and marine industries, with significant economic and ecological consequences. Specifically, biofouling on immersed hull surfaces generates increased drag and thus requires increased fuel consumption to maintain speed. Considerable effort has been spent developing techniques to prevent and control biofouling, but with limited success. Control methods that have proven to be effective are costly, time consuming, or negatively affect the environment. Recently, aeration via bubble injection along submerged surfaces has been shown to achieve long-lasting antifouling effects, and is the only effective non-toxic method available. An understanding of the basic mechanisms by which bubble-induced flow impedes biofouling is lacking, but is essential for the design of large-scale systems. We present results from an experimental investigation of several bubble induced flow fields over an inclined plate with simultaneous measurements of the fluid velocity and bubble characteristics using Digital article Image Velocimetry and high speed digital video. Trajectories of representative larval organisms are also resolved and linked with the flow field measurements to determine the mechanisms responsible for biofouling prevention.

A computational efficient modelling of laminar separation bubbles

NASA Technical Reports Server (NTRS)

Dini, Paolo; Maughmer, Mark D.

1990-01-01

In predicting the aerodynamic characteristics of airfoils operating at low Reynolds numbers, it is often important to account for the effects of laminar (transitional) separation bubbles. Previous approaches to the modelling of this viscous phenomenon range from fast but sometimes unreliable empirical correlations for the length of the bubble and the associated increase in momentum thickness, to more accurate but significantly slower displacement-thickness iteration methods employing inverse boundary-layer formulations in the separated regions. Since the penalty in computational time associated with the more general methods is unacceptable for airfoil design applications, use of an accurate yet computationally efficient model is highly desirable. To this end, a semi-empirical bubble model was developed and incorporated into the Eppler and Somers airfoil design and analysis program. The generality and the efficiency was achieved by successfully approximating the local viscous/inviscid interaction, the transition location, and the turbulent reattachment process within the framework of an integral boundary-layer method. Comparisons of the predicted aerodynamic characteristics with experimental measurements for several airfoils show excellent and consistent agreement for Reynolds numbers from 2,000,000 down to 100,000.

Numerical modeling of the 3D dynamics of ultrasound contrast agent microbubbles using the boundary integral method

NASA Astrophysics Data System (ADS)

Wang, Qianxi; Manmi, Kawa; Calvisi, Michael L.

2015-02-01

Ultrasound contrast agents (UCAs) are microbubbles stabilized with a shell typically of lipid, polymer, or protein and are emerging as a unique tool for noninvasive therapies ranging from gene delivery to tumor ablation. While various models have been developed to describe the spherical oscillations of contrast agents, the treatment of nonspherical behavior has received less attention. However, the nonspherical dynamics of contrast agents are thought to play an important role in therapeutic applications, for example, enhancing the uptake of therapeutic agents across cell membranes and tissue interfaces, and causing tissue ablation. In this paper, a model for nonspherical contrast agent dynamics based on the boundary integral method is described. The effects of the encapsulating shell are approximated by adapting Hoff's model for thin-shell, spherical contrast agents. A high-quality mesh of the bubble surface is maintained by implementing a hybrid approach of the Lagrangian method and elastic mesh technique. The numerical model agrees well with a modified Rayleigh-Plesset equation for encapsulated spherical bubbles. Numerical analyses of the dynamics of UCAs in an infinite liquid and near a rigid wall are performed in parameter regimes of clinical relevance. The oscillation amplitude and period decrease significantly due to the coating. A bubble jet forms when the amplitude of ultrasound is sufficiently large, as occurs for bubbles without a coating; however, the threshold amplitude required to incite jetting increases due to the coating. When a UCA is near a rigid boundary subject to acoustic forcing, the jet is directed towards the wall if the acoustic wave propagates perpendicular to the boundary. When the acoustic wave propagates parallel to the rigid boundary, the jet direction has components both along the wave direction and towards the boundary that depend mainly on the dimensionless standoff distance of the bubble from the boundary. In all cases, the jet directions for the coated and uncoated bubble are similar but the jet width and jet velocity are smaller for a coated bubble. The effects of shell thickness and shell viscosity are analyzed and determined to affect the bubble dynamics, including jet development.

Genetic adaptation to captivity can occur in a single generation

PubMed Central

Christie, Mark R.; Marine, Melanie L.; French, Rod A.; Blouin, Michael S.

2012-01-01

Captive breeding programs are widely used for the conservation and restoration of threatened and endangered species. Nevertheless, captive-born individuals frequently have reduced fitness when reintroduced into the wild. The mechanism for these fitness declines has remained elusive, but hypotheses include environmental effects of captive rearing, inbreeding among close relatives, relaxed natural selection, and unintentional domestication selection (adaptation to captivity). We used a multigenerational pedigree analysis to demonstrate that domestication selection can explain the precipitous decline in fitness observed in hatchery steelhead released into the Hood River in Oregon. After returning from the ocean, wild-born and first-generation hatchery fish were used as broodstock in the hatchery, and their offspring were released into the wild as smolts. First-generation hatchery fish had nearly double the lifetime reproductive success (measured as the number of returning adult offspring) when spawned in captivity compared with wild fish spawned under identical conditions, which is a clear demonstration of adaptation to captivity. We also documented a tradeoff among the wild-born broodstock: Those with the greatest fitness in a captive environment produced offspring that performed the worst in the wild. Specifically, captive-born individuals with five (the median) or more returning siblings (i.e., offspring of successful broodstock) averaged 0.62 returning offspring in the wild, whereas captive-born individuals with less than five siblings averaged 2.05 returning offspring in the wild. These results demonstrate that a single generation in captivity can result in a substantial response to selection on traits that are beneficial in captivity but severely maladaptive in the wild. PMID:22184236

Tooth damage in captive orcas (Orcinus orca).

PubMed

Jett, John; Visser, Ingrid N; Ventre, Jeffrey; Waltz, Jordan; Loch, Carolina

2017-12-01

Tooth damage as a result of oral stereotypies is evident in captive orca, yet little research on the topic exists. This study examines the associations between dental pathology, sex, facility, duration of captivity and other factors in captive orca. We evaluated mandibular and maxillary teeth from dental images of 29 captive orca owned by a US-based theme park. Each tooth was scored for coronal wear, wear at or below gum line and bore holes. Fractured and missing teeth were also noted. Summary statistics described the distribution and severity of pathologies; inferential statistics examined how pathologies differed between sexes, between wild-captured and captive-born orcas and between captive orca at four facilities. We also evaluated how dental pathology and duration of captivity were related. Approximately 24% of whales exhibited "major" to "extreme" mandibular coronal tooth wear, with coronal wear and wear at or below gum line highly correlated. More than 60% of mandibular teeth 2 and 3 exhibited fractures. Bore holes were observed primarily among anterior mandibular teeth, with more than 61% of teeth 2 and 3 bearing evidence of having been drilled. Four of five orca with the highest age-adjusted tooth pathology indices were captive-born. Various dental pathologies were observed across all whales, with pathologies beginning at a young age. Oral stereotypies exhibited by captive orca contributed to the observed dental damage. By making dental and health records of captive whales publicly available, the theme park industry is uniquely positioned to provide further insight into dental pathology and resultant health consequences in captive orca. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bubble coalescence in a Newtonian fluid

NASA Astrophysics Data System (ADS)

Garg, Vishrut; Basaran, Osman

2017-11-01

Bubble coalescence plays a central role in the hydrodynamics of gas-liquid systems such as bubble column reactors, spargers, and foams. Two bubbles approaching each other at velocity V coalesce when the thin film between them ruptures, which is often the rate-limiting step. Experimental studies of this system are difficult, and recent works provide conflicting results on the effect of V on coalescence times. We simulate the head-on approach of two bubbles of equal radii R in an incompressible Newtonian fluid (density ρ, viscosity μ, and surface tension σ) by solving numerically the free boundary problem comprised of the Navier Stokes and continuity equations. Simulations are made challenging by the existence of highly disparate lengthscales, i.e. film thickness and drop radii, which are resolved by using the method of elliptic mesh generation. For a given liquid, the bubbles are shown to coalesce for all velocities below a critical value. The effects of Ohnesorge number Oh = μ /√{ ρσR } on coalescence time and critical velocity are also investigated.

Acoustic bubble dynamics in a microvessel surrounded by elastic material

NASA Astrophysics Data System (ADS)

Wang, S. P.; Wang, Q. X.; Leppinen, D. M.; Zhang, A. M.; Liu, Y. L.

2018-01-01

This paper is concerned with microbubble dynamics in a blood vessel surrounded by elastic tissue subject to ultrasound, which are associated with important applications in medical ultrasonics. Both the blood flow inside the vessel and the tissue flow external to the vessel are modeled using the potential flow theory coupled with the boundary element method. The elasticity of tissue is modeled through the inclusion of a pressure term in the dynamic boundary condition at the interface between the two fluids. Weakly viscous effects are considered using viscous potential flow theory. The numerical model is validated by comparison with the theoretical results of the Rayleigh-Plesset equation for spherical bubbles, the numerical results for acoustic bubbles in an unbounded flow, and the experimental images for a spark generated bubble in a rigid circular cylinder. Numerical analyses are then performed for the bubble oscillation, jet formation and penetration through the bubble, and the deformation of the vessel wall in terms of the ultrasound amplitude and the vessel radius.

Cavitation Bubble Streaming in Ultrasonic-Standing-Wave Field

NASA Astrophysics Data System (ADS)

Nomura, Shinfuku; Mukasa, Shinobu; Kuroiwa, Masaya; Okada, Yasuyuki; Murakami, Koichi

2005-05-01

The mechanism of cavitation bubble streaming by ultrasonic vibration in a water tank was experimentally investigated. A standard ultrasonic cleaner unit with a resonant frequency of 40 kHz was used as an ultrasonic generator. The behavior of the streaming was visualized by the schlieren method and sonochemical luminescence, and the velocity of the streaming was measured by laser Doppler velocity measurement equipment (LDV). The cavitation bubble streaming has two structures. A cavitation cloud, which consists of many cavitation bubbles, is shaped like a facing pair of bowls with a diameter of approximately 1/3 the wavelength of the standing wave, and moves inside the standing-wave field with a velocity of 30 to 60 mm/s. The cavitation bubbles move intensely in the cloud with a velocity of 5 m/s at an ultrasonic output power of 75 W. The streaming is completely different from conventional acoustic streaming. Also the cavitation bubble is generated neither at the pressure node nor at the antinode.

Switchable Underwater Bubble Wettability on Laser-Induced Titanium Multiscale Micro-/Nanostructures by Vertically Crossed Scanning.

PubMed

Jiao, Yunlong; Li, Chuanzong; Wu, Sizhu; Hu, Yanlei; Li, Jiawen; Yang, Liang; Wu, Dong; Chu, Jiaru

2018-05-16

We present here a kind of novel multiscale TiO 2 square micropillar arrays on titanium sheets through vertically crossed scanning of femtosecond laser. This multiscale micro-/nanostructure is ascribed to the combination of laser ablation/shock compression/debris self-deposition, which shows superaerophobicity in water with a very small sliding angle. The laser-induced sample displays switchable bubble wettability in water via heating in a dark environment and ultraviolet (UV) irradiation in alcohol. After heating in a dark environment (0.5 h), the ablated titanium surface shows superaerophilicity in water with a bubble contact angle (BCA) of ∼4°, which has a great ability of capturing bubbles in water. After UV irradiation in alcohol (1 h), the sample recovered its superaerophobicity in water and the BCA turns into 156°. The mechanism of reversible switching is believed as the chemical conversion between Ti-OH and Ti-O. It is worth noting that our proposed switching strategy is time-saving and the switch wetting cycle costs only 1.5 h. Then we repeat five switching cycles on the reversibility and the method shows excellent reproducibility and stability. Moreover, laser-induced samples with different scanning spacing (50-120 μm) are fabricated and all of them show switchable underwater bubble wettability via the above tunable methods. Finally, we fabricate hybrid-patterned microstructures to show different patterned bubbles in water on the heated samples. We believe the original works will provide some new insights to researchers in bubble manipulation and gas collection fields.

Visualisation of gas-liquid mass transfer around a rising bubble in a quiescent liquid using an oxygen sensitive dye

NASA Astrophysics Data System (ADS)

Dietrich, Nicolas; Hebrard, Gilles

2018-02-01

An approach for visualizing and measuring the mass transfer around a single bubble rising in a quiescent liquid is reported. A colorimetric technique, developed by (Dietrich et al. Chem Eng Sci 100:172-182, 2013) using an oxygen sensitive redox dye was implemented. It was based on the reduction of the colorimetric indicator in presence of oxygen, this reduction being catalysed by sodium hydroxide and glucose. In this study, resazurin was selected because it offered various reduced forms with colours ranging from transparent (without oxygen) to pink (in presence of oxygen). These advantages made it possible to visualize the spatio-temporal oxygen mass transfer around rising bubbles. Images were recorded by a CCD camera and, after post-processing, the shape, size, and velocity of the bubbles were measured and the colours around the bubbles mapped. A calibration, linking the level of colour with the dissolved oxygen concentration, enabled colour maps to be converted into oxygen concentration fields. A rheoscopic fluid was used to visualize the wake of the bubbles. A calculation method was also developed to determine the transferred oxygen fluxes around bubbles of two sizes (d = 0.82 mm and d = 2.12 mm) and the associated liquid-side mass transfer coefficients. The results compared satisfactorily with classical global measurements made by oxygen micro-sensors or from the classical models. This study thus constitutes a striking example of how this new colorimetric method could become a remarkable tool for exploring gas-liquid mass transfer in fluids.

Visualisation of gas-liquid mass transfer around a rising bubble in a quiescent liquid using an oxygen sensitive dye

NASA Astrophysics Data System (ADS)

Dietrich, Nicolas; Hebrard, Gilles

2018-07-01

An approach for visualizing and measuring the mass transfer around a single bubble rising in a quiescent liquid is reported. A colorimetric technique, developed by (Dietrich et al. Chem Eng Sci 100:172-182, 2013) using an oxygen sensitive redox dye was implemented. It was based on the reduction of the colorimetric indicator in presence of oxygen, this reduction being catalysed by sodium hydroxide and glucose. In this study, resazurin was selected because it offered various reduced forms with colours ranging from transparent (without oxygen) to pink (in presence of oxygen). These advantages made it possible to visualize the spatio-temporal oxygen mass transfer around rising bubbles. Images were recorded by a CCD camera and, after post-processing, the shape, size, and velocity of the bubbles were measured and the colours around the bubbles mapped. A calibration, linking the level of colour with the dissolved oxygen concentration, enabled colour maps to be converted into oxygen concentration fields. A rheoscopic fluid was used to visualize the wake of the bubbles. A calculation method was also developed to determine the transferred oxygen fluxes around bubbles of two sizes (d = 0.82 mm and d = 2.12 mm) and the associated liquid-side mass transfer coefficients. The results compared satisfactorily with classical global measurements made by oxygen micro-sensors or from the classical models. This study thus constitutes a striking example of how this new colorimetric method could become a remarkable tool for exploring gas-liquid mass transfer in fluids.

Shape and evolution of wind-blown bubbles of massive stars: on the effect of the interstellar magnetic field

NASA Astrophysics Data System (ADS)

van Marle, A. J.; Meliani, Z.; Marcowith, A.

2015-12-01

Context. The winds of massive stars create large (>10 pc) bubbles around their progenitors. As these bubbles expand they encounter the interstellar coherent magnetic field which, depending on its strength, can influence the shape of the bubble. Aims: We wish to investigate if, and how much, the interstellar magnetic field can contribute to the shape of an expanding circumstellar bubble around a massive star. Methods: We use the MPI-AMRVAC code to make magneto-hydrodynamical simulations of bubbles, using a single star model, combined with several different field strengths: B = 5, 10, and 20 μG for the interstellar magnetic field. This covers the typical field strengths of the interstellar magnetic fields found in the galactic disk and bulge. Furthermore, we present two simulations that include both a 5 μG interstellar magnetic field and a warm (10 000 K) interstellar medium (ISM) and two different ISM densities to demonstrate how the magnetic field can combine with other external factors to influence the morphology of the circumstellar bubbles. Results: Our results show that low magnetic fields, as found in the galactic disk, inhibit the growth of the circumstellar bubbles in the direction perpendicular to the field. As a result, the bubbles become ovoid, rather than spherical. Strong interstellar fields, such as observed for the galactic bulge, can completely stop the expansion of the bubble in the direction perpendicular to the field, leading to the formation of a tube-like bubble. When combined with an ISM that is both warm and high density the bubble is greatly reduced in size, causing a dramatic change in the evolution of temporary features inside the bubble such as Wolf-Rayet ring nebulae. Conclusions: The magnetic field of the interstellar medium can affect the shape of circumstellar bubbles. This effect may have consequences for the shape and evolution of circumstellar nebulae and supernova remnants, which are formed within the main wind-blown bubble. Appendices and movies associated to Figs. A.1-A.12 are available in electronic form at http://www.aanda.org

Comparison of two different methods of preoperative marking for toric intraocular lens implantation: bubble marker versus pendulum marker.

PubMed

Farooqui, Javed Hussain; Koul, Archana; Dutta, Ranjan; Shroff, Noshir Minoo

2016-01-01

To compare the accuracy of two different methods of preoperative marking for toric intraocular lens (IOL) implantation, bubble marker versus pendulum marker, as a means of establishing the reference point for the final alignment of the toric IOL to achieve an outcome as close as possible to emmetropia. Toric IOLs were implanted in 180 eyes of 110 patients. One group (55 patients) had preoperative marking of both eyes done with bubble marker (ASICO AE-2791TBL) and the other group (55 patients) with pendulum marker (Rumex(®)3-193). Reference marks were placed at 3-, 6-, and 9-o'clock positions on the limbus. Slit-lamp photographs were analyzed using Adobe Photoshop (version 7.0). Amount of alignment error (in degrees) induced in each group was measured. Mean absolute rotation error in the preoperative marking in the horizontal axis was 2.42±1.71 in the bubble marker group and 2.83±2.31in the pendulum marker group (P=0.501). Sixty percent of the pendulum group and 70% of the bubble group had rotation error ≤3 (P=0.589), and 90% eyes of the pendulum group and 96.7% of the bubble group had rotation error ≤5 (P=0.612). Both preoperative marking techniques result in approximately 3 of alignment error. Both marking techniques are simple, predictable, reproducible and easy to perform.

Two types of nonlinear wave equations for diffractive beams in bubbly liquids with nonuniform bubble number density.

PubMed

Kanagawa, Tetsuya

2015-05-01

This paper theoretically treats the weakly nonlinear propagation of diffracted sound beams in nonuniform bubbly liquids. The spatial distribution of the number density of the bubbles, initially in a quiescent state, is assumed to be a slowly varying function of the spatial coordinates; the amplitude of variation is assumed to be small compared to the mean number density. A previous derivation method of nonlinear wave equations for plane progressive waves in uniform bubbly liquids [Kanagawa, Yano, Watanabe, and Fujikawa (2010). J. Fluid Sci. Technol. 5(3), 351-369] is extended to handle quasi-plane beams in weakly nonuniform bubbly liquids. The diffraction effect is incorporated by adding a relation that scales the circular sound source diameter to the wavelength into the original set of scaling relations composed of nondimensional physical parameters. A set of basic equations for bubbly flows is composed of the averaged equations of mass and momentum, the Keller equation for bubble wall, and supplementary equations. As a result, two types of evolution equations, a nonlinear Schrödinger equation including dissipation, diffraction, and nonuniform effects for high-frequency short-wavelength case, and a Khokhlov-Zabolotskaya-Kuznetsov equation including dispersion and nonuniform effects for low-frequency long-wavelength case, are derived from the basic set.

On the Application of Image Processing Methods for Bubble Recognition to the Study of Subcooled Flow Boiling of Water in Rectangular Channels

PubMed Central

Paz, Concepción; Conde, Marcos; Porteiro, Jacobo; Concheiro, Miguel

2017-01-01

This work introduces the use of machine vision in the massive bubble recognition process, which supports the validation of boiling models involving bubble dynamics, as well as nucleation frequency, active site density and size of the bubbles. The two algorithms presented are meant to be run employing quite standard images of the bubbling process, recorded in general-purpose boiling facilities. The recognition routines are easily adaptable to other facilities if a minimum number of precautions are taken in the setup and in the treatment of the information. Both the side and front projections of subcooled flow-boiling phenomenon over a plain plate are covered. Once all of the intended bubbles have been located in space and time, the proper post-process of the recorded data become capable of tracking each of the recognized bubbles, sketching their trajectories and size evolution, locating the nucleation sites, computing their diameters, and so on. After validating the algorithm’s output against the human eye and data from other researchers, machine vision systems have been demonstrated to be a very valuable option to successfully perform the recognition process, even though the optical analysis of bubbles has not been set as the main goal of the experimental facility. PMID:28632158

Manipulation of Microbubble Clusters Using Focused Ultrasound

NASA Astrophysics Data System (ADS)

Matsuzaki, Hironobu; Osaki, Taichi; Kawaguchi, Kei; Unga, Johan; Ichiyanagi, Mitsuhisa; Azuma, Takashi; Suzuki, Ryo; Maruyama, Kazuo; Takagi, Shu

2017-11-01

In recent years, microbubbles (MBs) are expected to be utilized for the ultrasound drug delivery system (DDS). For the MB-DDS, it is important to establish a method of controlling bubbles and bubble clusters using ultrasound field. The objective of this study is to clarify behaviors of bubble clusters with various physical conditions. MBs in the ultrasound field are subjected to the primary Bjerknes force. The force traps MBs at the focal region of the focused ultrasound field. The trapped MBs form a bubble cluster at the region. A bubble cluster continues growing with absorbing surrounding bubbles until it reaches a maximum size beyond which it disappears from the focal region. In the present study, two kinds of MBs are used for the experiment. One is Sonazoid with average diameter of 2.6 um and resonant frequency of 5 MHz. The other is developed by Teikyo Univ., with average diameter of 1.5 um and presumed resonant frequency of 4 MHz. The bubble cluster's behaviors are analyzed using the high-speed camera. Sonazoid clusters have larger critical size than the other in every frequency, and its cluster size is inversely proportional to the ultrasound frequency, while Teikyo-bubble clusters have different tendency. These results are discussed in the presentation.

Numerical modeling of ultrasonic cavitation in ionic liquids

NASA Astrophysics Data System (ADS)

Calvisi, Michael L.; Elder, Ross M.

2017-11-01

Ionic liquids have favorable properties for sonochemistry applications in which the high temperatures and pressures achieved by cavitation bubbles are important drivers of chemical processes. Two different numerical models are presented to simulate ultrasonic cavitation in ionic liquids, each with different capabilities and physical assumptions. A model based on a compressible form of the Rayleigh-Plesset equation (RPE) simulates ultrasonic cavitation of a spherical bubble with a homogeneous interior, incorporating evaporation and condensation at the bubble surface, and temperature-varying thermodynamic properties in the interior. A second, more computationally intensive model of a spherical bubble uses the finite element method (FEM) and accounts for spatial variations in pressure and temperature throughout the flow domain. This model provides insight into heat transfer across the bubble surface and throughout the bubble interior and exterior. Parametric studies are presented for sonochemistry applications involving ionic liquids as a solvent, examining a range of realistic ionic liquid properties and initial conditions to determine their effect on temperature and pressure. Results from the two models are presented for parametric variations including viscosity, thermal conductivity, water content of the ionic liquid solvent, acoustic frequency, and initial bubble pressure. An additional study performed with the FEM model examines thermal penetration into the surrounding ionic liquid during bubble oscillation. The results suggest the prospect of tuning ionic liquid properties for specific applications.

μ-PIV measurements of the ensemble flow fields surrounding a migrating semi-infinite bubble.

PubMed

Yamaguchi, Eiichiro; Smith, Bradford J; Gaver, Donald P

2009-08-01

Microscale particle image velocimetry (μ-PIV) measurements of ensemble flow fields surrounding a steadily-migrating semi-infinite bubble through the novel adaptation of a computer controlled linear motor flow control system. The system was programmed to generate a square wave velocity input in order to produce accurate constant bubble propagation repeatedly and effectively through a fused glass capillary tube. We present a novel technique for re-positioning of the coordinate axis to the bubble tip frame of reference in each instantaneous field through the analysis of the sudden change of standard deviation of centerline velocity profiles across the bubble interface. Ensemble averages were then computed in this bubble tip frame of reference. Combined fluid systems of water/air, glycerol/air, and glycerol/Si-oil were used to investigate flows comparable to computational simulations described in Smith and Gaver (2008) and to past experimental observations of interfacial shape. Fluorescent particle images were also analyzed to measure the residual film thickness trailing behind the bubble. The flow fields and film thickness agree very well with the computational simulations as well as existing experimental and analytical results. Particle accumulation and migration associated with the flow patterns near the bubble tip after long experimental durations are discussed as potential sources of error in the experimental method.

Effect of phytoplackton-derived organic matter on the behavior of marine aerosols

NASA Astrophysics Data System (ADS)

Fuentes, E.; Coe, H.; McFiggans, G.; Green, D.

2009-04-01

The presence of significant concentrations of organic material in marine aerosols has been appreciated for several decades; however, only recently has significant progress been made towards demonstrating that this organic content is biogenically formed. Biogenic organics of placktonic life origin are incorporated in marine aerosol composition as a result of bubble bursting/breaking waves mechanisms that occur at the ocean surface. The presence of organic surfactants in the marine aerosol composition might have a significant impact on the properties of the generated aerosols by affecting the particles surface tension and solution balance properties. Nevertheless, it remains uncertain the role of such organics on the physical-chemical behavior of marine aerosols. In this work an experimental study was performed in order to determine the influence of biogenic marine organic compounds on the size distribution, hygroscopicity and cloud-nucleating properties of marine aerosols. For the experimental study a laboratory water recirculation system (bubble tank), designed for the simulation of bubble-burst aerosol formation, was used as marine aerosol generator. The bubble spectra produced by such system was characterized by means of an optical bubble measuring device (BMS) and it was found to be consistent with oceanic bubble spectra properties. Seawater proxy solutions were prepared from laboratory biologically-synthesized exudates produced by oceanic representative algal species and introduced in the tank for the generation of marine aerosol by bubble bursting. Two experimental methods were employed for seawater proxies preparation: the formation of surface monolayers from the biogenic surfactants extracted by a solid phase extraction technique (monolayer method) and the mixing of the exudates in the sea salt water bulk (bulk mixing method). Particle size distribution, hygroscopicity and cloud condensation nuclei experiments for different monolayers, and exudate mixtures were performed. This contribution provides an overview of the experimental study conducted and the most relevant results found in this research work.

Remobilizing the Interfaces of Thermocapillary Driven Bubbles Retarded by the Adsorption of a Surfactant Impurity on the Bubble Surface

NASA Technical Reports Server (NTRS)

Palaparthi, Ravi; Maldarelli, Charles; Papageorgiou, Dimitri; Singh, Bhim S. (Technical Monitor)

2000-01-01

Thermocapillary migration is a method for moving bubbles in space in the absence of buoyancy. A temperature gradient is applied to the continuous phase in which a bubble is situated, and the applied gradient impressed on the bubble surface causes one pole of the drop to be cooler than the opposite pole. As the surface tension is a decreasing function of temperature, the cooler pole pulls at the warmer pole, creating a flow which propels the bubble in the direction of the warmer fluid. A major impediment to the practical use of thermocapillarity to direct the movement of bubbles in space is the fact that surfactant impurities which are unavoidably present in the continuous phase can significantly reduce the migration velocity. A surfactant impurity adsorbed onto the bubble interface is swept to the trailing end of the bubble. When bulk concentrations are low (which is the case with an impurity), diffusion of surfactant to the front end is slow relative to convection, and surfactant collects at the back end of the bubble. Collection at the back lowers the surface tension relative to the front end setting up a reverse tension gradient. For buoyancy driven bubble motions in the absence of a thermocapillarity, the tension gradient opposes the surface flow, and reduces the surface and terminal velocities (the interface becomes more solid-like). When thermocapillary forces are present, the reverse tension gradient set up by the surfactant accumulation reduces the temperature tension gradient, and decreases to near zero the thermocapillary velocity. The objective of our research is to develop a method for enhancing the thermocapillary migration of bubbles which have been retarded by the adsorption onto the bubble surface of a surfactant impurity, Our remobilization theory proposes to use surfactant molecules which kinetically rapidly exchange between the bulk and the surface and are at high bulk concentrations. Because the remobilizing surfactant is present at much higher concentrations than the impurity, it adsorbs to the bubble much faster than the impurity when the bubble is formed, and thereby prevents the impurity from adsorbing onto the surface. In addition the rapid kinetic exchange and high bulk concentration maintain a saturated surface with a uniform surface concentrations. This prevents retarding surface tension gradients and keeps the velocity high. In our first report last year, we detailed experimental results which verified the theory of remobilization in ground based experiments in which the steady velocity of rising bubbles was measured in a continuous phase consisting of a glycerol/water mixture containing a polyethylene glycol surfactant C12E6 (CH3(CH2)11(OCH2CH2)6OH). In our report this year, we detail our efforts to describe theoretically the remobilization observed. We construct a model in which a bubble rises steadily by buoyancy in a continuous (Newtonian) viscous fluid containing surfactant with a uniform far field bulk concentration. We account for the effects of inertia as well as viscosity in the flow in the continuous phase caused by the bubble motion (order one Reynolds number), and we assume that the bubble shape remains spherical (viscous and inertial forces are smaller than capillary forces, i e. small Weber and capillary numbers). The surfactant distribution is calculated by solving the mass transfer equations including convection and diffusion in the bulk, and finite kinetic exchange the bulk and the surface. Convective effects dominate diffusive mass transfer in the bulk of the liquid (high Peclet numbers) except in a thin boundary layer near the surface. A finite volume method is used to numerically solve the hydrodynamic and mass transfer equations on a staggered grid which accounts specifically for the thin boundary layer. We present the results of the nondimensional drag as a function of the bulk concentration of surfactant for different rates of kinetic exchange, from which we develop criteria for the concentration necessary to develop a prescribed degree of remobilization. The criteria compare favorably with the experimental results.

Injuries and Illnesses of Vietnam War POWs Revisited: 2. Army Risk Factors

DTIC Science & Technology

2016-01-12

concerning symptoms and conditions which occurred during captivity (as described in the history section of the IMEF). Berg and Richlin emphasized...evaluated the effects of captivity from the perspective of ICD9-CM diagnostic categories (i.e., systems level). From this perspective, the relationship...included age at time of captivity , length of captivity (months), length of solitary confinement (weeks), self-reported captivity medical problems

Injuries and Illnesses of Vietnam War POWs Revisited: I. Navy Risk Factors

DTIC Science & Technology

2016-01-05

concerning symptoms and conditions which occurred during captivity (as described in the history section of the IMEF). Berg and Richlin emphasized...individual diagnoses, we evaluated the effects of captivity from the perspective of ICD9-CM diagnostic categories (i.e., systems level). From this...These risk factors included age at time of captivity , length of captivity (months), length of solitary confinement (weeks), self-reported captivity

Injuries and Illnesses of Vietnam War POWs Revisited: 3. Marine Corps Risk Factors

DTIC Science & Technology

2016-01-12

also presented concerning symptoms and conditions which occurred during captivity (as described in the history section of the IMEF). Berg and...diagnoses, we evaluated the effects of captivity from the perspective of ICD9-CM diagnostic categories (i.e., systems level). From this perspective...risk factors included age at time of captivity , length of captivity (months), length of solitary confinement (weeks), self-reported captivity

Effect of captivity on the blood composition of Spanish ibex (Capra pyrenaica hispanica).

PubMed

Peinado, V I; Fernandez-Arias, A; Zabala, J L; Palomeque, J

1995-12-02

Blood analyses of seven free-ranging Spanish ibex (Capra pyrenaica hispanica) captured from the wild and then held in captivity were used to determine the physiological changes in some haematological parameters and serum chemistry values during captivity. The captive animals had a higher haematocrit and haemoglobin concentration and larger numbers of erythrocytes than the same animals when they were captured. In addition, the absolute numbers of leucocytes and lymphocytes decreased progressively during captivity. Significant differences were found for some of the biochemical variables between the captive ibex and free-ranging animals.

Rearing environment influences boldness and prey acquisition behavior, and brain and lens development of bull trout

USGS Publications Warehouse

Brignon, William R.; Pike, Martin M.; Ebbesson, Lars O.E.; Schaller, Howard A.; Peterson, James T.; Schreck, Carl B.

2018-01-01

Animals reared in barren captive environments exhibit different developmental trajectories and behaviors than wild counterparts. Hence, the captive phenotypes may influence the success of reintroduction and recovery programs for threatened and endangered species. We collected wild bull trout embryos from the Metolius River Basin, Oregon and reared them in differing environments to better understand how captivity affects the bull trout Salvelinus confluentusphenotype. We compared the boldness and prey acquisition behaviors and development of the brain and eye lens of bull trout reared in conventional barren and more structurally complex captive environments with that of wild fish. Wild fish and captive reared fish from complex habitats exhibited a greater level of boldness and prey acquisition ability, than fish reared in conventional captive environments. In addition, the eye lens of conventionally reared bull trout was larger than complex reared captive fish or same age wild fish. Interestingly, we detected wild fish had a smaller relative cerebellum than either captive reared treatment. Our results suggest that rearing fish in more complex captive environments can create a more wild-like phenotype than conventional rearing practices. A better understanding of the effects of captivity on the development and behavior of bull trout can inform rearing and reintroduction programs though prediction of the performance of released individuals.

Study on bubble column humidification and dehumidification system for coal mine wastewater treatment.

PubMed

Gao, Penghui; Zhang, Meng; Du, Yuji; Cheng, Bo; Zhang, Donghai

2018-04-01

Water is important resource for human survival and development. Coal mine wastewater (CMW) is a byproduct of the process of coal mining, which is about 7.0 × 10 10 m 3 in China in 2016. Considering coal mine wastewater includes different ingredients, a new bubble column humidification and dehumidification system is proposed for CMW treatment. The system is mainly composed of a bubble column humidification and dehumidification unit, solar collector, fan and water tank, in which air is used as a circulating medium. The system can avoid water treatment component blocking for reverse osmosis (RO) and multi effect distillation (MED) dealing with CMW, and produce water greenly. By analysis of heat and mass transfer, the effects of solar radiation, air bubble velocity and mine water temperature on water treatment production characteristics are studied. Compared with other methods, thermal energy consumption (TEC) of bubble column humidification and dehumidification (BCHD) is moderate, which is about 700 kJ/kg (powered by solar energy). The results would provide a new method for CMW treatment and insights into the efficient coal wastewater treatment, besides, it helps to identify the parameters for the technology development in mine water treatment.

Effects of tissue stiffness, ultrasound frequency, and pressure on histotripsy-induced cavitation bubble behavior.

PubMed

Vlaisavljevich, Eli; Lin, Kuang-Wei; Warnez, Matthew T; Singh, Rahul; Mancia, Lauren; Putnam, Andrew J; Johnsen, Eric; Cain, Charles; Xu, Zhen

2015-03-21

Histotripsy is an ultrasound ablation method that controls cavitation to fractionate soft tissue. In order to effectively fractionate tissue, histotripsy requires cavitation bubbles to rapidly expand from nanometer-sized initial nuclei into bubbles often larger than 50 µm. Using a negative pressure high enough to initiate a bubble cloud and expand bubbles to a sufficient size, histotripsy has been shown capable of completely fractionating soft tissue into acelluar debris resulting in effective tissue removal. Previous work has shown that the histotripsy process is affected by tissue mechanical properties with stiffer tissues showing increased resistance to histotripsy fractionation, which we hypothesize to be caused by impeded bubble expansion in stiffer tissues. In this study, the hypothesis that increases in tissue stiffness cause a reduction in bubble expansion was investigated both theoretically and experimentally. High speed optical imaging was used to capture a series of time delayed images of bubbles produced inside mechanically tunable agarose tissue phantoms using histotripsy pulses produced by 345 kHz, 500 kHz, 1.5 MHz, and 3 MHz histotripsy transducers. The results demonstrated a significant decrease in maximum bubble radius (Rmax) and collapse time (tc) with both increasing Young's modulus and increasing frequency. Furthermore, results showed that Rmax was not increased by raising the pressure above the intrinsic threshold. Finally, this work demonstrated the potential of using a dual-frequency strategy to modulate the expansion of histotripsy bubbles. Overall, the results of this study improve our understanding of how tissue stiffness and ultrasound parameters affect histotripsy-induced bubble behavior and provide a rational basis to tailor acoustic parameters for treatment of the specific tissues of interest.

Effects of tissue stiffness, ultrasound frequency, and pressure on histotripsy-induced cavitation bubble behavior

NASA Astrophysics Data System (ADS)

Vlaisavljevich, Eli; Lin, Kuang-Wei; Warnez, Matthew T.; Singh, Rahul; Mancia, Lauren; Putnam, Andrew J.; Johnsen, Eric; Cain, Charles; Xu, Zhen

2015-03-01

Histotripsy is an ultrasound ablation method that controls cavitation to fractionate soft tissue. In order to effectively fractionate tissue, histotripsy requires cavitation bubbles to rapidly expand from nanometer-sized initial nuclei into bubbles often larger than 50 µm. Using a negative pressure high enough to initiate a bubble cloud and expand bubbles to a sufficient size, histotripsy has been shown capable of completely fractionating soft tissue into acelluar debris resulting in effective tissue removal. Previous work has shown that the histotripsy process is affected by tissue mechanical properties with stiffer tissues showing increased resistance to histotripsy fractionation, which we hypothesize to be caused by impeded bubble expansion in stiffer tissues. In this study, the hypothesis that increases in tissue stiffness cause a reduction in bubble expansion was investigated both theoretically and experimentally. High speed optical imaging was used to capture a series of time delayed images of bubbles produced inside mechanically tunable agarose tissue phantoms using histotripsy pulses produced by 345 kHz, 500 kHz, 1.5 MHz, and 3 MHz histotripsy transducers. The results demonstrated a significant decrease in maximum bubble radius (Rmax) and collapse time (tc) with both increasing Young’s modulus and increasing frequency. Furthermore, results showed that Rmax was not increased by raising the pressure above the intrinsic threshold. Finally, this work demonstrated the potential of using a dual-frequency strategy to modulate the expansion of histotripsy bubbles. Overall, the results of this study improve our understanding of how tissue stiffness and ultrasound parameters affect histotripsy-induced bubble behavior and provide a rational basis to tailor acoustic parameters for treatment of the specific tissues of interest.

A comparative study of the speeds attained by captive cheetahs during the enrichment practice of the "cheetah run".

PubMed

Quirke, Thomas; O'Riordan, Ruth; Davenport, John

2013-01-01

The enrichment practice of the "cheetah run" is becoming increasingly popular within zoological institutions as a method to enrich captive cheetahs. A lure moving at speed represents an artificial prey item that the cursorial cheetah can pursue, therefore allowing it to perform an important hunting behavior within a captive setting. This study was conducted in order to highlight how employing different forms of this type of enrichment may influence its efficacy. This is important in relation to the future development of an optimum type of "cheetah run" enrichment which maximizes the potential beneficial effects and therefore positively impacts upon cheetah welfare in captivity. Video recordings were carried out at three separate institutions (Fota Wildlife Park, Ireland; Ann van Dyk Cheetah Centre, South Africa; Cheetah Conservation Fund, Namibia). Randomization tests were carried out to compare the highest speeds attained between males and females, trained and untrained cheetahs and also between the three institutions. Females and trained individuals reached significantly higher speeds compared with males and untrained individuals, respectively. The only significant difference between the three institutions was between the Ann van Dyk Cheetah Centre and the Cheetah Conservation Fund, where cheetahs at the Ann van Dyk center reached significantly higher speeds. The current study represents the first detailed study of any aspect of the "cheetah run" across multiple institutions. It also includes the first quantification of the speed of cheetahs in captivity in relation to differing enrichment practices. © 2013 Wiley Periodicals, Inc.

Using tri-axial accelerometers to identify wild polar bear behaviors

USGS Publications Warehouse

Pagano, Anthony M.; Rode, Karyn D.; Cutting, A.; Owen, M.A.; Jensen, S.; Ware, J.V.; Robbins, C.T.; Durner, George M.; Atwood, Todd C.; Obbard, M.E.; Middel, K.R.; Thiemann, G.W.; Williams, T.M.

2017-01-01

Tri-axial accelerometers have been used to remotely identify the behaviors of a wide range of taxa. Assigning behaviors to accelerometer data often involves the use of captive animals or surrogate species, as their accelerometer signatures are generally assumed to be similar to those of their wild counterparts. However, this has rarely been tested. Validated accelerometer data are needed for polar bears Ursus maritimus to understand how habitat conditions may influence behavior and energy demands. We used accelerometer and water conductivity data to remotely distinguish 10 polar bear behaviors. We calibrated accelerometer and conductivity data collected from collars with behaviors observed from video-recorded captive polar bears and brown bears U. arctos, and with video from camera collars deployed on free-ranging polar bears on sea ice and on land. We used random forest models to predict behaviors and found strong ability to discriminate the most common wild polar bear behaviors using a combination of accelerometer and conductivity sensor data from captive or wild polar bears. In contrast, models using data from captive brown bears failed to reliably distinguish most active behaviors in wild polar bears. Our ability to discriminate behavior was greatest when species- and habitat-specific data from wild individuals were used to train models. Data from captive individuals may be suitable for calibrating accelerometers, but may provide reduced ability to discriminate some behaviors. The accelerometer calibrations developed here provide a method to quantify polar bear behaviors to evaluate the impacts of declines in Arctic sea ice.

Bubble Motion through a Generalized Power-Law Fluid Flowing in a Vertical Tube

PubMed Central

Mukundakrishnan, Karthik; Eckmann, David M.; Ayyaswamy, P. S.

2009-01-01

Intravascular gas embolism may occur with decompression in space flight, as well as during cardiac and vascular surgery. Intravascular bubbles may be deposited into any end organ, such as the heart or the brain. Surface interactions between the bubble and the endothelial cells lining the vasculature result in serious impairment of blood flow and can lead to heart attack, stroke, or even death. To develop effective therapeutic strategies, there is a need for understanding the dynamics of bubble motion through blood and its interaction with the vessel wall through which it moves. Toward this goal, we numerically investigate the axisymmetric motion of a bubble moving through a vertical circular tube in a shear-thinning generalized power-law fluid, using a front-tracking method. The formulation is characterized by the inlet Reynolds number, capillary number, Weber number, and Froude number. The flow dynamics and the associated wall shear stresses are documented for a combination of two different inlet flow conditions (inlet Reynolds numbers) and three different effective bubble radii (ratio of the undeformed bubble radii to the tube radii). The results of the non-Newtonian model are then compared with that of the model assuming a Newtonian blood viscosity. Specifically, for an almost occluding bubble (effective bubble radius = 0.9), the wall shear stress and the bubble residence time are compared for both Newtonian and non-Newtonian cases. Results show that at low shear rates, for a given pressure gradient the residence time for a non-Newtonian flow is higher than that for a Newtonian flow. PMID:19426324

Formation of Nitrogen Bubbles During Solidification of Duplex Stainless Steels

NASA Astrophysics Data System (ADS)

Dai, Kaiju; Wang, Bo; Xue, Fei; Liu, Shanshan; Huang, Junkai; Zhang, Jieyu

2018-04-01

The nucleation and growth of nitrogen bubbles for duplex stainless steels are of great significance for the formation mechanism of bubbles during solidification. In the current study, numerical method and theoretical analysis of formula derivation were used to study the formation of nitrogen bubbles during solidification. The critical sizes of the bubble for homogeneous nucleation and heterogeneous nucleation at the solid-liquid interface during solidification were derived theoretically by the classical nucleation theory. The results show that the calculated values for the solubility of nitrogen in duplex stainless steel are in good agreement with the experimental values which are quoted by references: for example, when the temperature T = 1823 K and the nitrogen partial pressure P_{{N2 }} = 40P^{Θ} , the calculated value (0.8042 wt pct) for the solubility of Fe-12Cr alloy nitrogen in molten steel is close to the experimental value (0.780 wt pct). Moreover, the critical radii for homogeneous nucleation and heterogeneous nucleation are identical during solidification. On the one hand, with the increasing temperature or the melt depth, the critical nucleation radius of bubbles at the solid-liquid interface increases, but the bubble growth rate decreases. On the other hand, with the decreasing initial content of nitrogen or the cooling rate, the critical nucleation radius of bubbles at the solid-liquid interface increases, but the bubble growth rate decreases. Furthermore, when the melt depth is greater than the critical depth, which is determined by the technological conditions, the change in the Gibbs free energy for the nucleation is not conducive enough to form new bubbles.

Comparison of three different prehospital wrapping methods for preventing hypothermia - a crossover study in humans

PubMed Central

2011-01-01

Background Accidental hypothermia increases mortality and morbidity in trauma patients. Various methods for insulating and wrapping hypothermic patients are used worldwide. The aim of this study was to compare the thermal insulating effects and comfort of bubble wrap, ambulance blankets / quilts, and Hibler's method, a low-cost method combining a plastic outer layer with an insulating layer. Methods Eight volunteers were dressed in moistened clothing, exposed to a cold and windy environment then wrapped using one of the three different insulation methods in random order on three different days. They were rested quietly on their back for 60 minutes in a cold climatic chamber. Skin temperature, rectal temperature, oxygen consumption were measured, and metabolic heat production was calculated. A questionnaire was used for a subjective evaluation of comfort, thermal sensation, and shivering. Results Skin temperature was significantly higher 15 minutes after wrapping using Hibler's method compared with wrapping with ambulance blankets / quilts or bubble wrap. There were no differences in core temperature between the three insulating methods. The subjects reported more shivering, they felt colder, were more uncomfortable, and had an increased heat production when using bubble wrap compared with the other two methods. Hibler's method was the volunteers preferred method for preventing hypothermia. Bubble wrap was the least effective insulating method, and seemed to require significantly higher heat production to compensate for increased heat loss. Conclusions This study demonstrated that a combination of vapour tight layer and an additional dry insulating layer (Hibler's method) is the most efficient wrapping method to prevent heat loss, as shown by increased skin temperatures, lower metabolic rate and better thermal comfort. This should then be the method of choice when wrapping a wet patient at risk of developing hypothermia in prehospital environments. PMID:21699720

Numerical study of ambient pressure for laser-induced bubble near a rigid boundary

NASA Astrophysics Data System (ADS)

Li, BeiBei; Zhang, HongChao; Han, Bing; Lu, Jian

2012-07-01

The dynamics of the laser-induced bubble at different ambient pressures was numerically studied by Finite Volume Method (FVM). The velocity of the bubble wall, the liquid jet velocity at collapse, and the pressure of the water hammer while the liquid jet impacting onto the boundary are found to increase nonlinearly with increasing ambient pressure. The collapse time and the formation time of the liquid jet are found to decrease nonlinearly with increasing ambient pressure. The ratios of the jet formation time to the collapse time, and the displacement of the bubble center to the maximal radius while the jet formation stay invariant when ambient pressure changes. These ratios are independent of ambient pressure.

Comparative skull analysis suggests species-specific captivity-related malformation in lions (Panthera leo).

PubMed

Saragusty, Joseph; Shavit-Meyrav, Anat; Yamaguchi, Nobuyuki; Nadler, Rona; Bdolah-Abram, Tali; Gibeon, Laura; Hildebrandt, Thomas B; Shamir, Merav H

2014-01-01

Lion (Panthera leo) populations have dramatically decreased worldwide with a surviving population estimated at 32,000 across the African savannah. Lions have been kept in captivity for centuries and, although they reproduce well, high rates of stillbirths as well as morbidity and mortality of neonate and young lions are reported. Many of these cases are associated with bone malformations, including foramen magnum (FM) stenosis and thickened tentorium cerebelli. The precise causes of these malformations and whether they are unique to captive lions remain unclear. To test whether captivity is associated with FM stenosis, we evaluated 575 lion skulls of wild (N = 512) and captive (N = 63) origin. Tiger skulls (N = 276; 56 captive, 220 wild) were measured for comparison. While no differences were found between males and females or between subadults and adults in FM height (FMH), FMH of captive lions (17.36±3.20 mm) was significantly smaller and with greater variability when compared to that in wild lions (19.77±2.11 mm). There was no difference between wild (18.47±1.26 mm) and captive (18.56±1.64 mm) tigers in FMH. Birth origin (wild vs. captive) as a factor for FMH remained significant in lions even after controlling for age and sex. Whereas only 20/473 wild lions (4.2%) had FMH equal to or smaller than the 5th percentile of the wild population (16.60 mm), this was evident in 40.4% (23/57) of captive lion skulls. Similar comparison for tigers found no differences between the captive and wild populations. Lions with FMH equal to or smaller than the 5th percentile had wider skulls with smaller cranial volume. Cranial volume remained smaller in both male and female captive lions when controlled for skull size. These findings suggest species- and captivity-related predisposition for the pathology in lions.

Comparative Skull Analysis Suggests Species-Specific Captivity-Related Malformation in Lions (Panthera leo)

PubMed Central

Saragusty, Joseph; Shavit-Meyrav, Anat; Yamaguchi, Nobuyuki; Nadler, Rona; Bdolah-Abram, Tali; Gibeon, Laura; Hildebrandt, Thomas B.; Shamir, Merav H.

2014-01-01

Lion (Panthera leo) populations have dramatically decreased worldwide with a surviving population estimated at 32,000 across the African savannah. Lions have been kept in captivity for centuries and, although they reproduce well, high rates of stillbirths as well as morbidity and mortality of neonate and young lions are reported. Many of these cases are associated with bone malformations, including foramen magnum (FM) stenosis and thickened tentorium cerebelli. The precise causes of these malformations and whether they are unique to captive lions remain unclear. To test whether captivity is associated with FM stenosis, we evaluated 575 lion skulls of wild (N = 512) and captive (N = 63) origin. Tiger skulls (N = 276; 56 captive, 220 wild) were measured for comparison. While no differences were found between males and females or between subadults and adults in FM height (FMH), FMH of captive lions (17.36±3.20 mm) was significantly smaller and with greater variability when compared to that in wild lions (19.77±2.11 mm). There was no difference between wild (18.47±1.26 mm) and captive (18.56±1.64 mm) tigers in FMH. Birth origin (wild vs. captive) as a factor for FMH remained significant in lions even after controlling for age and sex. Whereas only 20/473 wild lions (4.2%) had FMH equal to or smaller than the 5th percentile of the wild population (16.60 mm), this was evident in 40.4% (23/57) of captive lion skulls. Similar comparison for tigers found no differences between the captive and wild populations. Lions with FMH equal to or smaller than the 5th percentile had wider skulls with smaller cranial volume. Cranial volume remained smaller in both male and female captive lions when controlled for skull size. These findings suggest species- and captivity-related predisposition for the pathology in lions. PMID:24718586

The Effects of Captivity on the Mammalian Gut Microbiome

PubMed Central

McKenzie, Valerie J.; Song, Se Jin; Delsuc, Frédéric; Prest, Tiffany L.; Oliverio, Angela M.; Korpita, Timothy M.; Alexiev, Alexandra; Amato, Katherine R.; Metcalf, Jessica L.; Kowalewski, Martin; Avenant, Nico L.; Link, Andres; Di Fiore, Anthony; Seguin-Orlando, Andaine; Feh, Claudia; Orlando, Ludovic; Mendelson, Joseph R.; Sanders, Jon; Knight, Rob

2017-01-01

Synopsis Recent studies increasingly note the effect of captivity or the built environment on the microbiome of humans and other animals. As symbiotic microbes are essential to many aspects of biology (e.g., digestive and immune functions), it is important to understand how lifestyle differences can impact the microbiome, and, consequently, the health of hosts. Animals living in captivity experience a range of changes that may influence the gut bacteria, such as diet changes, treatments, and reduced contact with other individuals, species and variable environmental substrates that act as sources of bacterial diversity. Thus far, initial results from previous studies point to a pattern of decreased bacterial diversity in captive animals. However, these studies are relatively limited in the scope of species that have been examined. Here we present a dataset that includes paired wild and captive samples from mammalian taxa across six Orders to investigate generalizable patterns of the effects captivity on mammalian gut bacteria. In comparing the wild to the captive condition, our results indicate that alpha diversity of the gut bacteria remains consistent in some mammalian hosts (bovids, giraffes, anteaters, and aardvarks), declines in the captive condition in some hosts (canids, primates, and equids), and increases in the captive condition in one host taxon (rhinoceros). Differences in gut bacterial beta diversity between the captive and wild state were observed for most of the taxa surveyed, except the even-toed ungulates (bovids and giraffes). Additionally, beta diversity variation was also strongly influenced by host taxonomic group, diet type, and gut fermentation physiology. Bacterial taxa that demonstrated larger shifts in relative abundance between the captive and wild states included members of the Firmicutes and Bacteroidetes. Overall, the patterns that we observe will inform a range of disciplines from veterinary practice to captive breeding efforts for biological conservation. Furthermore, bacterial taxa that persist in the captive state provide unique insight into symbiotic relationships with the host. PMID:28985326

The shape and motion of gas bubbles in a liquid flowing through a thin annulus

NASA Astrophysics Data System (ADS)

Lei, Qinghua; Xie, Zhihua; Pavlidis, Dimitrios; Salinas, Pablo; Veltin, Jeremy; Muggeridge, Ann; Pain, Christopher C.; Matar, Omar K.; Jackson, Matthew; Arland, Kristine; Gyllensten, Atle

2017-11-01

We study the shape and motion of gas bubbles in a liquid flowing through a horizontal or slightly-inclined thin annulus. Experimental data show that in the horizontal annulus, bubbles develop a unique ``tadpole'' shape with an elliptical cap and a highly-stretched tail, due to the confinement between the closely-spaced channel walls. As the annulus is inclined, the bubble tail tends to decrease in length, while the geometry of the cap remains almost invariant. To model the bubble evolution, the thin annulus is conceptualised as a ``Hele-Shaw'' cell in a curvilinear space. The three-dimensional flow within the cell is represented by a gap-averaged, two-dimensional model constrained by the same dimensionless quantities. The complex bubble dynamics are solved using a mixed control-volume finite-element method combined with interface-capturing and mesh adaptation techniques. A close match to the experimental data is achieved, both qualitatively and quantitatively, by the numerical simulations. The mechanism for the elliptical cap formation is interpreted based on an analogous irrotational flow field around a circular cylinder. The shape regimes of bubbles flowing through the thin annulus are further explored based on the simulation results. Funding from STATOIL gratefully acknowledged.

Simulation of bubble expansion and collapse in the vicinity of a free surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koukouvinis, P., E-mail: foivos.koukouvinis.1@city.ac.uk; Gavaises, M.; Supponen, O.

The present paper focuses on the numerical simulation of the interaction of laser-generated bubbles with a free surface, including comparison of the results with instances from high-speed videos of the experiment. The Volume Of Fluid method was employed for tracking liquid and gas phases while compressibility effects were introduced with appropriate equations of state for each phase. Initial conditions of the bubble pressure were estimated through the traditional Rayleigh Plesset equation. The simulated bubble expands in a non-spherically symmetric way due to the interference of the free surface, obtaining an oval shape at the maximum size. During collapse, a jetmore » with mushroom cap is formed at the axis of symmetry with the same direction as the gravity vector, which splits the initial bubble to an agglomeration of toroidal structures. Overall, the simulation results are in agreement with the experimental images, both quantitatively and qualitatively, while pressure waves are predicted both during the expansion and the collapse of the bubble. Minor discrepancies in the jet velocity and collapse rate are found and are attributed to the thermodynamic closure of the gas inside the bubble.« less

Dynamics of the liquid film around elongated bubbles rising in vertical capillaries

NASA Astrophysics Data System (ADS)

Magnini, Mirco; Khodaparast, Sepideh; Matar, Omar K.; Stone, Howard A.; Thome, John R.

2017-11-01

We performed a theoretical, numerical and experimental study on elongated bubbles rising in vertical tubes in co-current liquid flows. The flow conditions were characterized by capillary, Reynolds and Bond numbers within the range of Ca = 0.005 - 0.1 , Re = 1 - 2000 and Bo = 0 - 20 . Direct numerical simulations of the two-phase flows are run with a self-improved version of OpenFOAM, implementing a coupled Level Set and Volume of Fluid method. A theoretical model based on an extension of the traditional Bretherton theory, accounting for inertia and the gravity force, is developed to obtain predictions of the profiles of the front and rear menisci of the bubble, liquid film thickness and bubble velocity. Different from the traditional theory for bubbles rising in a stagnant liquid, the gravity force impacts the flow already when Bo < 4 . Gravity effects speed up the bubble compared to the Bo = 0 case, making the liquid film thicker and reducing the amplitude of the undulation on the surface of the bubble near its tail. Gravity effects are more apparent in the visco-capillary regime, i.e. when the Reynolds number is below 1.

Contact bubble bilayers with flush drainage.

PubMed

Iwamoto, Masayuki; Oiki, Shigetoshi

2015-03-16

Planar lipid bilayers have been used to form stable bilayers into which membrane proteins are reconstituted for measurements of their function under an applied membrane potential. Recently, a lipid bilayer membrane is formed by the apposition of two monolayers that line an oil-electrolyte interface. Here, a bilayer membrane system is developed with picoliter bubbles under mechanically and chemically manipulable conditions. A water bubble lined with a phospholipid monolayer is blown from a glass pipette into an oil phase. Two blowing pipettes are manipulated, and bubbles (each with a diameter of ~ 50 μm) are held side by side to form a bilayer, which is termed a contact bubble bilayer. With the electrode implemented in the blowing pipette, currents through the bilayer are readily measured. The intra-bubble pressure is varied with the pressure-controller, leading to various sizes of the bubble and the membrane area. A rapid solution exchange system is developed by introducing additional pressure-driven injection pipettes, and the blowing pipette works as a drain. The solution is exchanged within 20 ms. Also, an asymmetric membrane with different lipid composition of each leaflet is readily formed. Example applications of this versatile method are presented to characterize the function of ion channels.

Contact Bubble Bilayers with Flush Drainage

PubMed Central

Iwamoto, Masayuki; Oiki, Shigetoshi

2015-01-01

Planar lipid bilayers have been used to form stable bilayers into which membrane proteins are reconstituted for measurements of their function under an applied membrane potential. Recently, a lipid bilayer membrane is formed by the apposition of two monolayers that line an oil-electrolyte interface. Here, a bilayer membrane system is developed with picoliter bubbles under mechanically and chemically manipulable conditions. A water bubble lined with a phospholipid monolayer is blown from a glass pipette into an oil phase. Two blowing pipettes are manipulated, and bubbles (each with a diameter of ~ 50 μm) are held side by side to form a bilayer, which is termed a contact bubble bilayer. With the electrode implemented in the blowing pipette, currents through the bilayer are readily measured. The intra-bubble pressure is varied with the pressure-controller, leading to various sizes of the bubble and the membrane area. A rapid solution exchange system is developed by introducing additional pressure-driven injection pipettes, and the blowing pipette works as a drain. The solution is exchanged within 20 ms. Also, an asymmetric membrane with different lipid composition of each leaflet is readily formed. Example applications of this versatile method are presented to characterize the function of ion channels. PMID:25772819

Measurement and reduction of micro-bubble formation in high-viscosity fluids

NASA Astrophysics Data System (ADS)

Tom, Glenn; Liu, Wei

2012-03-01

Gases at high drive pressure can initially dissolve into the fluids used in lithography and other critical processes during the fabrication of integrated circuits. In the low pressure portion of the dispense train, the dissolved gases can revert to bubbles. These bubbles can: 1. Affect the compressibility of the working fluid and change the flow characteristics of the dispense heads which require frequent re-tuning of the coating tools. 2. Contribute to defect formation if the bubbles are trapped on the surface of the wafer. Photosensitive Polyimides (PI) have high viscosities (1000 to 20,000 cP). Because of the high viscosity, high-powered, expensive pumps are needed to effectively remove the fluid from its container. Suction from the pump filling cycle easily causes cavitation, which can create flow rate variability, and micro-bubble formation. It is a common practice to apply pressure to the PI resists to minimize cavitation in the pump. The trade-off to this practice is the entrainment (dissolution) of the drive gas into the resist and the risk of micro-bubbles forming later in the dispense train. In the current study, ATMI measured the effects of two methods of pressure dispense from the container on the amount of gas entrained in a viscous fluid: (1) indirect pressure dispense and (2) direct pressure dispense. The main analytical method employed to measure the amount of dissolved gases is a gas chromatograph (GC), which can measure the concentration of gases dissolved in a volatile fluid. It is not suitable to measure gases in low volatility fluids. The new test method developed, however, is capable of measuring dissolved gases in low volatility fluids.

Study of homogeneous bubble nucleation in liquid carbon dioxide by a hybrid approach combining molecular dynamics simulation and density gradient theory

NASA Astrophysics Data System (ADS)

Langenbach, K.; Heilig, M.; Horsch, M.; Hasse, H.

2018-03-01

A new method for predicting homogeneous bubble nucleation rates of pure compounds from vapor-liquid equilibrium (VLE) data is presented. It combines molecular dynamics simulation on the one side with density gradient theory using an equation of state (EOS) on the other. The new method is applied here to predict bubble nucleation rates in metastable liquid carbon dioxide (CO2). The molecular model of CO2 is taken from previous work of our group. PC-SAFT is used as an EOS. The consistency between the molecular model and the EOS is achieved by adjusting the PC-SAFT parameters to VLE data obtained from the molecular model. The influence parameter of density gradient theory is fitted to the surface tension of the molecular model. Massively parallel molecular dynamics simulations are performed close to the spinodal to compute bubble nucleation rates. From these simulations, the kinetic prefactor of the hybrid nucleation theory is estimated, whereas the nucleation barrier is calculated from density gradient theory. This enables the extrapolation of molecular simulation data to the whole metastable range including technically relevant densities. The results are tested against available experimental data and found to be in good agreement. The new method does not suffer from typical deficiencies of classical nucleation theory concerning the thermodynamic barrier at the spinodal and the bubble size dependence of surface tension, which is typically neglected in classical nucleation theory. In addition, the density in the center of critical bubbles and their surface tension is determined as a function of their radius. The usual linear Tolman correction to the capillarity approximation is found to be invalid.

Study of homogeneous bubble nucleation in liquid carbon dioxide by a hybrid approach combining molecular dynamics simulation and density gradient theory.

PubMed

Langenbach, K; Heilig, M; Horsch, M; Hasse, H

2018-03-28

A new method for predicting homogeneous bubble nucleation rates of pure compounds from vapor-liquid equilibrium (VLE) data is presented. It combines molecular dynamics simulation on the one side with density gradient theory using an equation of state (EOS) on the other. The new method is applied here to predict bubble nucleation rates in metastable liquid carbon dioxide (CO 2 ). The molecular model of CO 2 is taken from previous work of our group. PC-SAFT is used as an EOS. The consistency between the molecular model and the EOS is achieved by adjusting the PC-SAFT parameters to VLE data obtained from the molecular model. The influence parameter of density gradient theory is fitted to the surface tension of the molecular model. Massively parallel molecular dynamics simulations are performed close to the spinodal to compute bubble nucleation rates. From these simulations, the kinetic prefactor of the hybrid nucleation theory is estimated, whereas the nucleation barrier is calculated from density gradient theory. This enables the extrapolation of molecular simulation data to the whole metastable range including technically relevant densities. The results are tested against available experimental data and found to be in good agreement. The new method does not suffer from typical deficiencies of classical nucleation theory concerning the thermodynamic barrier at the spinodal and the bubble size dependence of surface tension, which is typically neglected in classical nucleation theory. In addition, the density in the center of critical bubbles and their surface tension is determined as a function of their radius. The usual linear Tolman correction to the capillarity approximation is found to be invalid.

Assortative mating among animals of captive and wild origin following experimental conservation releases

PubMed Central

Slade, Brendan; Parrott, Marissa L.; Paproth, Aleisha; Magrath, Michael J. L.; Gillespie, Graeme R.; Jessop, Tim S.

2014-01-01

Captive breeding is a high profile management tool used for conserving threatened species. However, the inevitable consequence of generations in captivity is broad scale and often-rapid phenotypic divergence between captive and wild individuals, through environmental differences and genetic processes. Although poorly understood, mate choice preference is one of the changes that may occur in captivity that could have important implications for the reintroduction success of captive-bred animals. We bred wild-caught house mice for three generations to examine mating patterns and reproductive outcomes when these animals were simultaneously released into multiple outdoor enclosures with wild conspecifics. At release, there were significant differences in phenotypic (e.g. body mass) and genetic measures (e.g. Gst and F) between captive-bred and wild adult mice. Furthermore, 83% of offspring produced post-release were of same source parentage, inferring pronounced assortative mating. Our findings suggest that captive breeding may affect mating preferences, with potentially adverse implications for the success of threatened species reintroduction programmes. PMID:25411380

The air-bubble method of locking central-vein catheters with acidified, concentrated sodium chloride as a bactericidal agent: in vitro studies.

PubMed

Moore, Harold L; Twardowski, Zbylut J

2003-10-01

Soft, cuffed indwelling catheters are used for hemodialysis access and intravenous infusions. The majority of these catheters are removed as a result of infection caused by contamination of the catheter hub during the connection/disconnection procedures. To prevent clot formation in the lumen, these catheters are routinely "locked" with heparin or some other anticoagulant. None of the anticoagulants commonly used as locking solutions demonstrates any significant bactericidal properties. The primary goal of this study was the development of a catheter locking method that retains anticoagulant properties at the catheter tip and bactericidal properties at the catheter hub. The second goal was to find a solution that possesses excellent bactericidal properties but is not detrimental in the event of injection into the patient's blood stream. The bactericidal properties of acidified, concentrated saline (ACS) were compared to concentrated trisodium citrate and to commonly used bactericidal agents such as povidone iodine, sodium hypochlorite, and chlorhexidine. In preliminary studies, the rate of diffusion of solutes was measured in glass tubes. In another set of experiments, the mixing of two solutions (anticoagulant and bactericide) separated by an air bubble ("air-bubble method") was observed in stationary and moving systems. The final series of studies compared the bactericidal properties of ACS to other bactericidal solutions mentioned above. The solutions diffused swiftly in the glass tubes, and by the third day, both solutions were mixed. The air-bubble method prevented mixing in both stationary and moving systems. The bactericidal properties of ACS were superior to all other tested solutions. The proposed method of catheter locking with anticoagulant at the catheter tip and ACS at the catheter hub separated by an air bubble is a promising technique and clinical studies are warranted.

A new method of derived equatorial plasma bubbles motion by tracing OI 630 nm emission all-sky images

NASA Astrophysics Data System (ADS)

Li, M.; Yu, T.; Chunliang, X.; Zuo, X.; Liu, Z.

2017-12-01

A new method for estimating the equatorial plasma bubbles (EPBs) motions from airglow emission all-sky images is presented in this paper. This method, which is called 'cloud-derived wind technology' and widely used in satellite observation of wind, could reasonable derive zonal and meridional velocity vectors of EPBs drifts by tracking a series of successive airglow 630.0 nm emission images. Airglow emission images data are available from an all sky airglow camera in Hainan Fuke (19.5°N, 109.2°E) supported by China Meridional Project, which can receive the 630.0nm emission from the ionosphere F region at low-latitudes to observe plasma bubbles. A series of pretreatment technology, e.g. image enhancement, orientation correction, image projection are utilized to preprocess the raw observation. Then the regions of plasma bubble extracted from the images are divided into several small tracing windows and each tracing window can find a target window in the searching area in following image, which is considered as the position tracing window moved to. According to this, velocities in each window are calculated by using the technology of cloud-derived wind. When applying the cloud-derived wind technology, the maximum correlation coefficient (MCC) and the histogram of gradient (HOG) methods to find the target window, which mean to find the maximum correlation and the minimum euclidean distance between two gradient histograms in respectively, are investigated and compared in detail. The maximum correlation method is fianlly adopted in this study to analyze the velocity of plasma bubbles because of its better performance than HOG. All-sky images from Hainan Fuke, between August 2014 and October 2014, are analyzed to investigate the plasma bubble drift velocities using MCC method. The data at different local time at 9 nights are studied and find that zonal drift velocity in different latitude at different local time ranges from 50 m/s to 180 m/s and there is a peak value at about 20°N. For comparison and validation, EPBs motions obtained from three traditional methods are also investigated and compared with MC method. The advantages and disadvantages of using cloud-derived wind technology to calculate EPB drift velocity are discussed.

Numerical study of wall effects on buoyant gas-bubble rise in a liquid-filled finite cylinder

PubMed Central

Mukundakrishnan, Karthik; Quan, Shaoping; Eckmann, David M.; Ayyaswamy, Portonovo S.

2009-01-01

The wall effects on the axisymmetric rise and deformation of an initially spherical gas bubble released from rest in a liquid-filled, finite circular cylinder are numerically investigated. The bulk and gas phases are considered incompressible and immiscible. The bubble motion and deformation are characterized by the Morton number (Mo), Eötvös number (Eo), Reynolds number (Re), Weber number (We), density ratio, viscosity ratio, the ratios of the cylinder height and the cylinder radius to the diameter of the initially spherical bubble (H* = H/d0, R* = R/d0). Bubble rise in liquids described by Eo and Mo combinations ranging from (1,0.01) to (277.5,0.092), as appropriate to various terminal state Reynolds numbers (ReT) and shapes have been studied. The range of terminal state Reynolds numbers includes 0.02 < ReT < 70. Bubble shapes at terminal states vary from spherical to intermediate spherical-cap–skirted. The numerical procedure employs a front tracking finite difference method coupled with a level contour reconstruction of the front. This procedure ensures a smooth distribution of the front points and conserves the bubble volume. For the wide range of Eo and Mo examined, bubble motion in cylinders of height H* = 8 and R* ≥ 3, is noted to correspond to the rise in an infinite medium, both in terms of Reynolds number and shape at terminal state. In a thin cylindrical vessel (small R*), the motion of the bubble is retarded due to increased total drag and the bubble achieves terminal conditions within a short distance from release. The wake effects on bubble rise are reduced, and elongated bubbles may occur at appropriate conditions. For a fixed volume of the bubble, increasing the cylinder radius may result in the formation of well-defined rear recirculatory wakes that are associated with lateral bulging and skirt formation. The paper includes figures of bubble shape regimes for various values of R*, Eo, Mo, and ReT. Our predictions agree with existing results reported in the literature. PMID:17930342

A comparative study of volatile contents of primitive arc bubble-bearing melt inclusions determined by Raman-spectroscopy and mass-balance versus experimental homogenization methods

NASA Astrophysics Data System (ADS)

Moore, L.; Mironov, N.; Portnyagin, M.; Gazel, E.; Bodnar, R. J.

2016-12-01

Primitive olivine-hosted melt inclusions (MI) are a useful means to estimate the pre-eruptive volatile contents of a volcanic melts but post-entrapment processes complicate this approach. In particular, crystallization of the host phase along the wall of the MI and diffusion of H+ through the host cause CO2 and potentially S or other volatiles to exsolve from the melt to a separate fluid bubble. Recently, experimental rehydration and Raman spectroscopy have become potential methods for restoring the volatile contents of MI by rehomogenization or through mass balance calculations respectively. In order to compare these two approaches, we have studied MI from a single suite of samples from Klyuchevsky volcano (Kamchatka Arc) that have been treated with both experimental rehydration and analyzed using Raman spectroscopy. The maximum MI CO2 contents are in agreement ( 4000 ppm) regardless of the method used to account for CO2 in the bubble, but there is significantly more scatter to lower values using the Raman method which can be attributed to uncertainty related to mass balance calculations and carbonate daughter minerals that have formed at the glass-bubble interface. The presence of S- and C-bearing daughter minerals on the surface of the bubble in unheated melt inclusions indicates that to obtain more confident results with Raman spectroscopy, naturally quenched MIs should be also shortly reheated to dissolve most or all the crystals at the glass-bubble interface. Concerning H2O, MI from the unheated tephra samples contain less H2O than rehydrated MI in lavas. Determining the original H2O content of rehydrated MI is difficult because the H2O concentration in the glass is controlled by the conditions during the rehydration experiment. Thus reconciling the initial H2O content in primitive arc MIs (and degree of H2O loss) still remains a challenging task.

22 CFR 192.42 - Applicable benefits for captives.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Applicable benefits for captives. 192.42 Section 192.42 Foreign Relations DEPARTMENT OF STATE HOSTAGE RELIEF VICTIMS OF TERRORISM COMPENSATION Educational Benefits for Captive Situations § 192.42 Applicable benefits for captives. (a) When authorized by...

22 CFR 192.42 - Applicable benefits for captives.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Applicable benefits for captives. 192.42 Section 192.42 Foreign Relations DEPARTMENT OF STATE HOSTAGE RELIEF VICTIMS OF TERRORISM COMPENSATION Educational Benefits for Captive Situations § 192.42 Applicable benefits for captives. (a) When authorized by...

22 CFR 192.42 - Applicable benefits for captives.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Applicable benefits for captives. 192.42 Section 192.42 Foreign Relations DEPARTMENT OF STATE HOSTAGE RELIEF VICTIMS OF TERRORISM COMPENSATION Educational Benefits for Captive Situations § 192.42 Applicable benefits for captives. (a) When authorized by...

22 CFR 192.42 - Applicable benefits for captives.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Applicable benefits for captives. 192.42 Section 192.42 Foreign Relations DEPARTMENT OF STATE HOSTAGE RELIEF VICTIMS OF TERRORISM COMPENSATION Educational Benefits for Captive Situations § 192.42 Applicable benefits for captives. (a) When authorized by...

22 CFR 192.42 - Applicable benefits for captives.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Applicable benefits for captives. 192.42 Section 192.42 Foreign Relations DEPARTMENT OF STATE HOSTAGE RELIEF VICTIMS OF TERRORISM COMPENSATION Educational Benefits for Captive Situations § 192.42 Applicable benefits for captives. (a) When authorized by...

49 CFR 533.5 - Requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... per gallon, in the model year specified as applicable: Table I Model year 2-wheel drive light trucks Captive imports Other 4-wheel drive light trucks Captive imports Other Limited product line light trucks... standard Captive imports Others 2-wheel drive light trucks Captive imports Others 4-wheel drive light...

49 CFR 533.5 - Requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... per gallon, in the model year specified as applicable: Table I Model year 2-wheel drive light trucks Captive imports Other 4-wheel drive light trucks Captive imports Other Limited product line light trucks... standard Captive imports Others 2-wheel drive light trucks Captive imports Others 4-wheel drive light...

49 CFR 533.5 - Requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... per gallon, in the model year specified as applicable: Table I Model year 2-wheel drive light trucks Captive imports Other 4-wheel drive light trucks Captive imports Other Limited product line light trucks... standard Captive imports Others 2-wheel drive light trucks Captive imports Others 4-wheel drive light...

50 CFR 17.44 - Special rules-fishes.

Code of Federal Regulations, 2012 CFR

2012-10-01

... captive-bred or grown in captivity for commercial purposes starting at least at the F1 generation in captivity (i.e., captive-bred for at least one generation). Beluga caviar. Processed unfertilized eggs from... PLANTS (CONTINUED) ENDANGERED AND THREATENED WILDLIFE AND PLANTS Threatened Wildlife § 17.44 Special...

50 CFR 17.44 - Special rules-fishes.

Code of Federal Regulations, 2011 CFR

2011-10-01

... captive-bred or grown in captivity for commercial purposes starting at least at the F1 generation in captivity (i.e., captive-bred for at least one generation). Beluga caviar. Processed unfertilized eggs from... PLANTS (CONTINUED) ENDANGERED AND THREATENED WILDLIFE AND PLANTS Threatened Wildlife § 17.44 Special...

50 CFR 17.44 - Special rules-fishes.

Code of Federal Regulations, 2010 CFR

2010-10-01

... captive-bred or grown in captivity for commercial purposes starting at least at the F1 generation in captivity (i.e., captive-bred for at least one generation). Beluga caviar. Processed unfertilized eggs from... PLANTS (CONTINUED) ENDANGERED AND THREATENED WILDLIFE AND PLANTS Threatened Wildlife § 17.44 Special...

50 CFR 17.44 - Special rules-fishes.

Code of Federal Regulations, 2013 CFR

2013-10-01

... captive-bred or grown in captivity for commercial purposes starting at least at the F1 generation in captivity (i.e., captive-bred for at least one generation). Beluga caviar. Processed unfertilized eggs from... PLANTS (CONTINUED) ENDANGERED AND THREATENED WILDLIFE AND PLANTS Threatened Wildlife § 17.44 Special...

Contact Lenses Wettability In Vitro: Effect of Surface-Active Ingredients

PubMed Central

Lin, Meng C.; Svitova, Tatyana F.

2010-01-01

Purpose To investigate the release of surface-active agents (surfactants) from unworn soft contact lenses and their influence on the lens surface wettability in vitro. Methods Surface tension (ST) of blister pack solutions was measured by pendant-drop technique. STs at the air-aqueous interface and contact angles (CAs) of four conventional and seven silicone hydrogel (SiH) soft contact lenses (SCLs) were evaluated in a dynamic-cycling regime using a modified captive-bubble tensiometer-goniometer. Measurements were performed immediately after removal from blister packs, and after soaking in a glass vial filled with a surfactant-free solution, which was replaced daily for one week. Lens surface wettability was expressed as adhesion energy (AE) according to Young’s equation. Results STs of all blister pack solutions were lower than the reference ST of pure water (72.5 mN/m), indicating the presence of surfactants. When lenses were depleted of surfactants by soaking, the STs of all studied lenses and advancing CAs of selected lenses increased (p < 0.001). Receding CAs of all studied lenses were 12° ± 5° and were not affected by the presence of surfactants. For most of the conventional lenses, the surface wettability was largely dependent on surfactants, and reduced significantly after surfactant depletion. In contrast, most SiH lenses exhibited stable and self-sustained surface wettability in vitro. Conclusions The manufacturer-added surfactants affected wetting properties of all studied SCLs, although to different degrees. PMID:20400924

Comparison of Serum Protein Electrophoresis Values in Wild and Captive Whooping Cranes ( Grus americana ).

PubMed

Hausmann, Jennifer C; Cray, Carolyn; Hartup, Barry K

2015-09-01

Protein electrophoresis of serum samples from endangered, wild whooping cranes ( Grus americana ) was performed to help assess the health of the only self-sustaining, migratory population in North America. Serum samples from wild adult cranes (n = 22) were taken at Aransas National Wildlife Refuge, Texas, USA during winter. Wild juvenile cranes (n = 26) were sampled at Wood Buffalo National Park, Northwest Territories, Canada, in midsummer. All captive crane samples were acquired from the International Crane Foundation, Baraboo, WI, USA. Captive adult cranes (n = 30) were sampled during annual examinations, and archived serum samples from captive juvenile cranes (n = 19) were selected to match the estimated age of wild juveniles. Wild juveniles had significantly lower concentrations of all protein fractions than wild adults, except for prealbumin and γ globulins. All protein fraction concentrations for wild juveniles were significantly lower compared with captive juveniles, except for prealbumin and γ globulins, which were higher. Wild adults had significantly greater γ globulin concentrations than captive adults. Captive juveniles had significantly lower prealbumin and albumin concentrations and albumin : globulin ratios than captive adults. The higher γ globulin concentrations in wild versus captive cranes are likely because of increased antigenic exposure and immune stimulation. Protein fraction concentrations vary significantly with age and natural history in this species. Reference intervals for serum protein electrophoresis results from captive adult whooping cranes are provided in this study.

Acoustic methods for cavitation mapping in biomedical applications

NASA Astrophysics Data System (ADS)

Wan, M.; Xu, S.; Ding, T.; Hu, H.; Liu, R.; Bai, C.; Lu, S.

2015-12-01

In recent years, cavitation is increasingly utilized in a wide range of applications in biomedical field. Monitoring the spatial-temporal evolution of cavitation bubbles is of great significance for efficiency and safety in biomedical applications. In this paper, several acoustic methods for cavitation mapping proposed or modified on the basis of existing work will be presented. The proposed novel ultrasound line-by-line/plane-by-plane method can depict cavitation bubbles distribution with high spatial and temporal resolution and may be developed as a potential standard 2D/3D cavitation field mapping method. The modified ultrafast active cavitation mapping based upon plane wave transmission and reception as well as bubble wavelet and pulse inversion technique can apparently enhance the cavitation to tissue ratio in tissue and further assist in monitoring the cavitation mediated therapy with good spatial and temporal resolution. The methods presented in this paper will be a foundation to promote the research and development of cavitation imaging in non-transparent medium.

Crystal front shape control by use of an additional heater in a Czochralski sapphire single crystal growth system

NASA Astrophysics Data System (ADS)

Hur, Min-Jae; Han, Xue-Feng; Choi, Ho-Gil; Yi, Kyung-Woo

2017-09-01

The quality of sapphire single crystals used as substrates for LED production is largely influenced by two defects: dislocation density and bubbles trapped in the crystal. In particular, the dislocation density has a higher value in sapphire grown by the Czochralski (CZ) method than by other methods. In the present study, we predict a decreased value for the convexity and thermal gradient at the crystal front (CF) through the use of an additional heater in an induction-heated CZ system. In addition, we develop a solute concentration model by which the location of bubble formation in CZ growth is calculated, and the results are compared with experimental results. We further calculate the location of bubble entrapment corresponding with the use of an additional heater. We find that sapphire crystal growth with an additional heater yields a decreased thermal gradient at the CF, together with decreased CF convexity, improved energy efficiency, and improvements in terms of bubble formation location.

Simulation of Interaction of Strong Shocks with Gas Bubbles using the Direct Simulation Monte Carlo Method

NASA Astrophysics Data System (ADS)

Puranik, Bhalchandra; Watvisave, Deepak; Bhandarkar, Upendra

2016-11-01

The interaction of a shock with a density interface is observed in several technological applications such as supersonic combustion, inertial confinement fusion, and shock-induced fragmentation of kidney and gall-stones. The central physical process in this interaction is the mechanism of the Richtmyer-Meshkov Instability (RMI). The specific situation where the density interface is initially an isolated spherical or cylindrical gas bubble presents a relatively simple geometry that exhibits all the essential RMI processes such as reflected and refracted shocks, secondary instabilities, turbulence and mixing of the species. If the incident shocks are strong, the calorically imperfect nature needs to be modelled. In the present work, we have carried out simulations of the shock-bubble interaction using the DSMC method for such situations. Specifically, an investigation of the shock-bubble interaction with diatomic gases involving rotational and vibrational excitations at high temperatures is performed, and the effects of such high temperature phenomena will be presented.

Cold Heat Release Characteristics of Solidified Oil Droplet-Water Solution Latent Heat Emulsion by Air Bubbles

NASA Astrophysics Data System (ADS)

Inaba, Hideo; Morita, Shin-Ichi

The present work investigates the cold heat-release characteristics of the solidified oil droplets (tetradecane, C14H30, freezing point 278.9 K)/water solution emulsion as a latent heat-storage material having a low melting point. An air bubbles-emulsion direct-contact heat exchange method is selected for the cold heat-results from the solidified oil droplet-emulsion layer. This type of direct-contact method results in the high thermal efficiency. The diameter of air bubbles in the emulsion increases as compared with that in the pure water. The air bubbles blown from a nozzle show a strong mixing behavior during rising in the emulsion. The temperature effectiveness, the sensible heat release time and the latent heat release time have been measured as experimental parameters. The useful nondimensional emulsion level equations for these parameters have been derived in terms of the nondimensional emalsion level expressed the emulsion layer dimensions, Reynolds number for air flow, Stefan number and heat capacity ratio.

Semi-automatic image analysis methodology for the segmentation of bubbles and drops in complex dispersions occurring in bioreactors

NASA Astrophysics Data System (ADS)

Taboada, B.; Vega-Alvarado, L.; Córdova-Aguilar, M. S.; Galindo, E.; Corkidi, G.

2006-09-01

Characterization of multiphase systems occurring in fermentation processes is a time-consuming and tedious process when manual methods are used. This work describes a new semi-automatic methodology for the on-line assessment of diameters of oil drops and air bubbles occurring in a complex simulated fermentation broth. High-quality digital images were obtained from the interior of a mechanically stirred tank. These images were pre-processed to find segments of edges belonging to the objects of interest. The contours of air bubbles and oil drops were then reconstructed using an improved Hough transform algorithm which was tested in two, three and four-phase simulated fermentation model systems. The results were compared against those obtained manually by a trained observer, showing no significant statistical differences. The method was able to reduce the total processing time for the measurements of bubbles and drops in different systems by 21-50% and the manual intervention time for the segmentation procedure by 80-100%.

Visualization of ultrasound induced cavitation bubbles using the synchrotron x-ray Analyzer Based Imaging technique.

PubMed

Izadifar, Zahra; Belev, George; Izadifar, Mohammad; Izadifar, Zohreh; Chapman, Dean

2014-12-07

Observing cavitation bubbles deep within tissue is very difficult. The development of a method for probing cavitation, irrespective of its location in tissues, would improve the efficiency and application of ultrasound in the clinic. A synchrotron x-ray imaging technique, which is capable of detecting cavitation bubbles induced in water by a sonochemistry system, is reported here; this could possibly be extended to the study of therapeutic ultrasound in tissues. The two different x-ray imaging techniques of Analyzer Based Imaging (ABI) and phase contrast imaging (PCI) were examined in order to detect ultrasound induced cavitation bubbles. Cavitation was not observed by PCI, however it was detectable with ABI. Acoustic cavitation was imaged at six different acoustic power levels and six different locations through the acoustic beam in water at a fixed power level. The results indicate the potential utility of this technique for cavitation studies in tissues, but it is time consuming. This may be improved by optimizing the imaging method.

A measurement model for real estate bubble size based on the panel data analysis: An empirical case study

PubMed Central

Liu, Fengyun; Liu, Deqiang; Malekian, Reza; Li, Zhixiong; Wang, Deqing

2017-01-01

Employing the fundamental value of real estate determined by the economic fundamentals, a measurement model for real estate bubble size is established based on the panel data analysis. Using this model, real estate bubble sizes in various regions in Japan in the late 1980s and in recent China are examined. Two panel models for Japan provide results, which are consistent with the reality in the 1980s where a commercial land price bubble appeared in most area and was much larger than that of residential land. This provides evidence of the reliability of our model, overcoming the limit of existing literature with this method. The same models for housing prices in China at both the provincial and city levels show that contrary to the concern of serious housing price bubble in China, over-valuing in recent China is much smaller than that in 1980s Japan. PMID:28273141

Control of flow separation in a turbulent boundary layer

NASA Astrophysics Data System (ADS)

Cho, Minjeong; Choi, Sangho; Choi, Haecheon

2015-11-01

Towards the development of successful control methods for separation delay in a turbulent boundary layer, we adopt a model flow field, in which a turbulent separation occurs above a flat plate (Na and Moin 1998 JFM), and apply controls to this flow for reducing the size of the separation bubble and investigating the interaction between the forcing and flow near the separation bubble. We provide a single-frequency forcing with zero net mass flow rate at the upstream of the separation bubble. At low forcing frequencies, spanwise vortices are generated and travel downstream, bringing high momentum toward the wall and reducing the size of the separation bubble. Also, these vortices cause the separation and reattachment points to travel downstream. On the other hand, at high forcing frequencies, the size of the separation bubble becomes smaller and larger in time, respectively, due to the pressure gradient alternating favorably and adversely in time. Supported by NRF-2011-0028032 and 2014048162.

A measurement model for real estate bubble size based on the panel data analysis: An empirical case study.

PubMed

Liu, Fengyun; Liu, Deqiang; Malekian, Reza; Li, Zhixiong; Wang, Deqing

2017-01-01

Employing the fundamental value of real estate determined by the economic fundamentals, a measurement model for real estate bubble size is established based on the panel data analysis. Using this model, real estate bubble sizes in various regions in Japan in the late 1980s and in recent China are examined. Two panel models for Japan provide results, which are consistent with the reality in the 1980s where a commercial land price bubble appeared in most area and was much larger than that of residential land. This provides evidence of the reliability of our model, overcoming the limit of existing literature with this method. The same models for housing prices in China at both the provincial and city levels show that contrary to the concern of serious housing price bubble in China, over-valuing in recent China is much smaller than that in 1980s Japan.

Bubble-based acoustic radiation force using chirp insonation to reduce standing wave effects.

PubMed

Erpelding, Todd N; Hollman, Kyle W; O'Donnell, Matthew

2007-02-01

Bubble-based acoustic radiation force can measure local viscoelastic properties of tissue. High intensity acoustic waves applied to laser-generated bubbles induce displacements inversely proportional to local Young's modulus. In certain instances, long pulse durations are desirable but are susceptible to standing wave artifacts, which corrupt displacement measurements. Chirp pulse acoustic radiation force was investigated as a method to reduce standing wave artifacts. Chirp pulses with linear frequency sweep magnitudes of 100, 200 and 300 kHz centered around 1.5 MHz were applied to glass beads within gelatin phantoms and laser-generated bubbles within porcine lenses. The ultrasound transducer was translated axially to vary standing wave conditions, while comparing displacements using chirp pulses and 1.5 MHz tone burst pulses of the same duration and peak rarefactional pressure. Results demonstrated significant reduction in standing wave effects using chirp pulses, with displacement proportional to acoustic intensity and bubble size.

Bubble-Based Acoustic Radiation Force Using Chirp Insonation to Reduce Standing Wave Effects

PubMed Central

Erpelding, Todd N.; Hollman, Kyle W.; O’Donnell, Matthew

2007-01-01

Bubble-based acoustic radiation force can measure local viscoelastic properties of tissue. High intensity acoustic waves applied to laser-generated bubbles induce displacements inversely proportional to local Young’s modulus. In certain instances, long pulse durations are desirable but are susceptible to standing wave artifacts, which corrupt displacement measurements. Chirp pulse acoustic radiation force was investigated as a method to reduce standing wave artifacts. Chirp pulses with linear frequency sweep magnitudes of 100, 200, and 300 kHz centered around 1.5 MHz were applied to glass beads within gelatin phantoms and laser-generated bubbles within porcine lenses. The ultrasound transducer was translated axially to vary standing wave conditions, while comparing displacements using chirp pulses and 1.5 MHz tone burst pulses of the same duration and peak rarefactional pressure. Results demonstrated significant reduction in standing wave effects using chirp pulses, with displacement proportional to acoustic intensity and bubble size. PMID:17306697

Bubble migration inside a liquid drop in a space laboratory

NASA Technical Reports Server (NTRS)

Annamalai, P.; Shankar, N.; Cole, R.; Subramanian, R. S.

1982-01-01

The design of experiments in materials processing for trials on board the Shuttle are described. Thermocapillary flows will be examined as an aid to mixing in the formation of glasses. Acoustically levitated molten glass spheres will be spot heated to induce surface flow away from the hot spot to induce mixing. The surface flows are also expected to cause internal convective motion which will drive entrained gas bubbles toward the hot spot, a process also enhanced by the presence of thermal gradients. The method is called fining, and will be augmented by rotation of the sphere to cause bubble migration toward the axes of rotation to form one large bubble which is more easily removed. Centering techniques to fix the maximum centering accuracy will also be tried. Ground-based studies of bubble migration in a rotating liquid and in a temperature gradient in a liquid drop are reviewed.

Bubble Entropy: An Entropy Almost Free of Parameters.

PubMed

Manis, George; Aktaruzzaman, Md; Sassi, Roberto

2017-11-01

Objective : A critical point in any definition of entropy is the selection of the parameters employed to obtain an estimate in practice. We propose a new definition of entropy aiming to reduce the significance of this selection. Methods: We call the new definition Bubble Entropy . Bubble Entropy is based on permutation entropy, where the vectors in the embedding space are ranked. We use the bubble sort algorithm for the ordering procedure and count instead the number of swaps performed for each vector. Doing so, we create a more coarse-grained distribution and then compute the entropy of this distribution. Results: Experimental results with both real and synthetic HRV signals showed that bubble entropy presents remarkable stability and exhibits increased descriptive and discriminating power compared to all other definitions, including the most popular ones. Conclusion: The definition proposed is almost free of parameters. The most common ones are the scale factor r and the embedding dimension m . In our definition, the scale factor is totally eliminated and the importance of m is significantly reduced. The proposed method presents increased stability and discriminating power. Significance: After the extensive use of some entropy measures in physiological signals, typical values for their parameters have been suggested, or at least, widely used. However, the parameters are still there, application and dataset dependent, influencing the computed value and affecting the descriptive power. Reducing their significance or eliminating them alleviates the problem, decoupling the method from the data and the application, and eliminating subjective factors. Objective : A critical point in any definition of entropy is the selection of the parameters employed to obtain an estimate in practice. We propose a new definition of entropy aiming to reduce the significance of this selection. Methods: We call the new definition Bubble Entropy . Bubble Entropy is based on permutation entropy, where the vectors in the embedding space are ranked. We use the bubble sort algorithm for the ordering procedure and count instead the number of swaps performed for each vector. Doing so, we create a more coarse-grained distribution and then compute the entropy of this distribution. Results: Experimental results with both real and synthetic HRV signals showed that bubble entropy presents remarkable stability and exhibits increased descriptive and discriminating power compared to all other definitions, including the most popular ones. Conclusion: The definition proposed is almost free of parameters. The most common ones are the scale factor r and the embedding dimension m . In our definition, the scale factor is totally eliminated and the importance of m is significantly reduced. The proposed method presents increased stability and discriminating power. Significance: After the extensive use of some entropy measures in physiological signals, typical values for their parameters have been suggested, or at least, widely used. However, the parameters are still there, application and dataset dependent, influencing the computed value and affecting the descriptive power. Reducing their significance or eliminating them alleviates the problem, decoupling the method from the data and the application, and eliminating subjective factors.

Mycobacterium tuberculosis Infection among Asian Elephants in Captivity.

PubMed

Simpson, Gary; Zimmerman, Ralph; Shashkina, Elena; Chen, Liang; Richard, Michael; Bradford, Carol M; Dragoo, Gwen A; Saiers, Rhonda L; Peloquin, Charles A; Daley, Charles L; Planet, Paul; Narachenia, Apurva; Mathema, Barun; Kreiswirth, Barry N

2017-03-01

Although awareness of tuberculosis among captive elephants is increasing, antituberculosis therapy for these animals is not standardized. We describe Mycobacterium tuberculosis transmission between captive elephants based on whole genome analysis and report a successful combination treatment. Infection control protocols and careful monitoring of treatment of captive elephants with tuberculosis are warranted.

50 CFR 17.44 - Special rules-fishes.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., fingerlings, or other products derived from Huso huso captive-bred or grown in captivity for commercial purposes starting at least at the F1 generation in captivity (i.e., captive-bred for at least one... PLANTS (CONTINUED) ENDANGERED AND THREATENED WILDLIFE AND PLANTS Threatened Wildlife § 17.44 Special...

50 CFR 17.41 - Special rules-birds.

Code of Federal Regulations, 2013 CFR

2013-10-01

... PLANTS (CONTINUED) ENDANGERED AND THREATENED WILDLIFE AND PLANTS Threatened Wildlife § 17.41 Special... have been met and you meet the following requirements: (i) Captive-bred specimens: The source code on... accompanying the specimen must be “F” (captive born), “C” (bred in captivity), or “D” (bred in captivity for...

Manipulation of micro-objects using acoustically oscillating bubbles based on the gas permeability of PDMS.

PubMed

Liu, Bendong; Tian, Baohua; Yang, Xu; Li, Mohan; Yang, Jiahui; Li, Desheng; Oh, Kwang W

2018-05-01

This paper presents a novel manipulation method for micro-objects using acoustically oscillating bubbles with a controllable position based on the gas permeability of polydimethylsiloxane. The oscillating bubble trapped within the side channel attracts the neighboring micro-objects, and the position of the air-liquid interface is controlled by generating temporary pressure difference between the side channel and the air channel. To demonstrate the feasibility of the method in technological applications, polystyrene microparticles of 10  μ m in diameter were successfully captured, transported, and released. The influence of pressure difference on the movement speed of the air-liquid interface was demonstrated in our experiments, and the manipulation performance was also characterized by varying the frequency of the acoustic excitation and the pressure difference. Since the bubble generation and the air-liquid interface movement in our manipulation method do not need any electrochemical reaction and any high temperature, this on-chip manipulation method provides a controllable, efficient, and noninvasive tool for handling micro-objects such as particles, cells, and other entities. The whole manipulation process, including capturing, transporting, and releasing of particles, spent less than 1 min. It can be used to select the cells and particles in the microfluidic device or change the cell culture medium.

Direct numerical simulation of reactor two-phase flows enabled by high-performance computing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Jun; Cambareri, Joseph J.; Brown, Cameron S.

Nuclear reactor two-phase flows remain a great engineering challenge, where the high-resolution two-phase flow database which can inform practical model development is still sparse due to the extreme reactor operation conditions and measurement difficulties. Owing to the rapid growth of computing power, the direct numerical simulation (DNS) is enjoying a renewed interest in investigating the related flow problems. A combination between DNS and an interface tracking method can provide a unique opportunity to study two-phase flows based on first principles calculations. More importantly, state-of-the-art high-performance computing (HPC) facilities are helping unlock this great potential. This paper reviews the recent researchmore » progress of two-phase flow DNS related to reactor applications. The progress in large-scale bubbly flow DNS has been focused not only on the sheer size of those simulations in terms of resolved Reynolds number, but also on the associated advanced modeling and analysis techniques. Specifically, the current areas of active research include modeling of sub-cooled boiling, bubble coalescence, as well as the advanced post-processing toolkit for bubbly flow simulations in reactor geometries. A novel bubble tracking method has been developed to track the evolution of bubbles in two-phase bubbly flow. Also, spectral analysis of DNS database in different geometries has been performed to investigate the modulation of the energy spectrum slope due to bubble-induced turbulence. In addition, the single-and two-phase analysis results are presented for turbulent flows within the pressurized water reactor (PWR) core geometries. The related simulations are possible to carry out only with the world leading HPC platforms. These simulations are allowing more complex turbulence model development and validation for use in 3D multiphase computational fluid dynamics (M-CFD) codes.« less

Polar bear encephalitis: establishment of a comprehensive next-generation pathogen analysis pipeline for captive and free-living wildlife.

PubMed

Szentiks, C A; Tsangaras, K; Abendroth, B; Scheuch, M; Stenglein, M D; Wohlsein, P; Heeger, F; Höveler, R; Chen, W; Sun, W; Damiani, A; Nikolin, V; Gruber, A D; Grobbel, M; Kalthoff, D; Höper, D; Czirják, G Á; Derisi, J; Mazzoni, C J; Schüle, A; Aue, A; East, M L; Hofer, H; Beer, M; Osterrieder, N; Greenwood, A D

2014-05-01

This report describes three possibly related incidences of encephalitis, two of them lethal, in captive polar bears (Ursus maritimus). Standard diagnostic methods failed to identify pathogens in any of these cases. A comprehensive, three-stage diagnostic 'pipeline' employing both standard serological methods and new DNA microarray and next generation sequencing-based diagnostics was developed, in part as a consequence of this initial failure. This pipeline approach illustrates the strengths, weaknesses and limitations of these tools in determining pathogen caused deaths in non-model organisms such as wildlife species and why the use of a limited number of diagnostic tools may fail to uncover important wildlife pathogens. Copyright © 2013 Elsevier Ltd. All rights reserved.

Role of monomer sequence and backbone chemistry in polypeptoid copolymers for marine antifouling coatings

NASA Astrophysics Data System (ADS)

Patterson, Anastasia; Wenning, Brandon; Rizis, Georgios; Calabrese, David; Finlay, John; Franco, Sofia; Clare, Anthony; Kramer, Edward; Ober, Christopher; Segalman, Rachel

The design rules elucidated in this work suggest that antifouling coatings bearing pendant peptoid side chains perform better overall in marine fouling tests than those with peptide side chains, with extremely low attachment of N. incerta and high removal of U. linza. This difference in performance is likely due to the lack of a hydrogen bond donor in the peptoid backbone. Furthermore, we show that the bulk polymer material of these hierarchical coatings (based on PEO or PDMS) plays a key role in determining both surface presentation and fouling release performance. We demonstrate these trends utilizing a modular coating based on a triblock copolymer consisting of polystyrene and a vinyl-containing midblock, to which sequence-defined pendant oligomers (peptides or peptoids with sequences of oligo-PEO and fluoroalkyl groups) are attached via thiol-ene ``click'' chemistry. Surface presentation was analyzed with X-ray photoelectron spectroscopy and captive bubble water contact angle, and antifouling performance was evaluated with attachment and removal bioassays of the marine macroalga U. linza and diatom N. incerta. NSF GRFP and ONR PECASE.

Dysfunction of pulmonary surfactant mediated by phospholipid oxidation is cholesterol-dependent.

PubMed

Al-Saiedy, Mustafa; Pratt, Ryan; Lai, Patrick; Kerek, Evan; Joyce, Heidi; Prenner, Elmar; Green, Francis; Ling, Chang-Chun; Veldhuizen, Ruud; Ghandorah, Salim; Amrein, Matthias

2018-04-01

Pulmonary surfactant forms a cohesive film at the alveolar air-lung interface, lowering surface tension, and thus reducing the work of breathing and preventing atelectasis. Surfactant function becomes impaired during inflammation due to degradation of the surfactant lipids and proteins by free radicals. In this study, we examine the role of reactive nitrogen (RNS) and oxygen (ROS) species on surfactant function with and without physiological cholesterol levels (5-10%). Surface activity was assessed in vitro in a captive bubble surfactometer (CBS). Surfactant chemistry, monolayer fluidity and thermodynamic behavior were also recorded before and after oxidation. We report that physiologic amounts of cholesterol combined with oxidation results in severe impairment of surfactant function. We also show that surfactant polyunsaturated phospholipids are the most susceptible to oxidative alteration. Membrane thermodynamic experiments showed significant surfactant film stiffening after free radical exposure in the presence of cholesterol. These results point to a previously unappreciated role for cholesterol in amplifying defects in surface activity caused by oxidation of pulmonary surfactant, a finding that may have implications for treating several lung diseases. Copyright © 2018 Elsevier B.V. All rights reserved.

Two-Phase Flow Model and Experimental Validation for Bubble Augmented Waterjet Propulsion Nozzle

NASA Astrophysics Data System (ADS)

Choi, J.-K.; Hsiao, C.-T.; Wu, X.; Singh, S.; Jayaprakash, A.; Chahine, G.

2011-11-01

The concept of thrust augmentation through bubble injection into a waterjet has been the subject of many patents and publications over the past several decades, and there are simplified computational and experimental evidence of thrust increase. In this work, we present more rigorous numerical and experimental studies which aim at investigating two-phase water jet propulsion systems. The numerical model is based on a Lagrangian-Eulerian method, which considers the bubbly mixture flow both in the microscopic level where individual bubble dynamics are tracked and in the macroscopic level where bubbles are collectively described by the local void fraction of the mixture. DYNAFLOW's unsteady RANS solver, 3DYNAFS-Vis is used to solve the macro level variable density mixture medium, and a fully unsteady two-way coupling between this and the bubble dynamics/tracking code 3DYNAFS-DSM is utilized. Validation studies using measurements in a half 3-D experimental setup composed of divergent and convergent sections are presented. Visualization of the bubbles, PIV measurements of the flow, bubble size and behavior are observed, and the measured flow field data are used to validate the models. Thrust augmentation as high as 50% could be confirmed both by predictions and by experiments. This work was supported by the Office of Naval Research under the contract N00014-07-C-0427, monitored by Dr. Ki-Han Kim.

Relating Venous Gas Emboli (VGE) Scores to Altitude Decompression Sickness (DCS) Symptoms

NASA Technical Reports Server (NTRS)

Pilmanis, A. A.; Kannan, N.; Krause, K. M.; Webb, J. T.

1999-01-01

Purpose. It is generally accepted that DCS symptoms are caused by gas bubbles in tissues. However, current technology of bubble detection only permits monitoring of circulating bubbles, primarily intracardiac. Since the majority of DCS symptoms appear to be caused by extravascular bubbles, it has been suggested that current bubble detection techniques target bubbles that are of importance in only a minority of DCS cases. The purpose of this study is to determine the relationships between measured VGE and DCS symptoms in human subjects exposed to altitude. Methods. The AFRL DCS Research Database contains records on 2044 subject-exposures to simulated altitudes in a hypobaric chamber. VGE monitoring was accomplished using Doppler/Echo Imaging techniques. The Spencer Scale was used to score the VGE. Reporting of DCS symptoms by the subject was the primary end-point of the exposures. Results: The Mantel- Haenzel test indicated a strong correlation between DCS and bubble grade (p-value =0.001). Conclusions. A positive correlation between increasing VGE scores and DCS symptoms, does not imply causatinn. If all non-zero VGE grades are considered, 45.9% of the cases had VGE, but no DCS symptoms. Conversely, almost 1 in 5 subject-exposures resulted in DCS with NO VGE detected. VGE scores are not . good predictors of altitude DCS symptoms and field use of bubble detection for DCS prevention is not supported by this study.

Detection and characterization of elongated bubbles and drops in two-phase flow using magnetic fields

NASA Astrophysics Data System (ADS)

Wiederhold, A.; Boeck, T.; Resagk, C.

2017-08-01

We report a method to detect and to measure the size and velocity of elongated bubbles or drops in a dispersed two-phase flow. The difference of the magnetic susceptibilities between two phases causes a force on the interface between both phases when it is exposed to an external magnetic field. The force is measured with a state-of-the-art electromagnetic compensation balance. While the front and the back of the bubble pass the magnetic field, two peaks in the force signal appear, which can be used to calculate the velocity and geometry parameters of the bubble. We achieve a substantial advantage over other bubble detection techniques because this technique is contactless, non-invasive, independent of the electrical conductivity and can be applied to opaque or aggressive fluids. The measurements are performed in an inclined channel with air bubbles and paraffin oil drops in water. The bubble length is in the range of 0.1-0.25 m and the bubble velocity lies between 0.02-0.22 m s-1. Furthermore we show that it is possible to apply this measurement principle for nondestructive testing (NDT) of diamagnetic and paramagnetic materials like metal, plastics or glass, provided that defects are in the range of 10‒2 m. This technique opens up new possibilities in industrial applications to measure two-phase flow parameters and in material testing.

A New Active Cavitation Mapping Technique for Pulsed HIFU Applications – Bubble Doppler

PubMed Central

Li, Tong; Khokhlova, Tatiana; Sapozhnikov, Oleg; Hwang, Joo Ha; Sapozhnikov, Oleg; O’Donnell, Matthew

2015-01-01

In this work, a new active cavitation mapping technique for pulsed high-intensity focused ultrasound (pHIFU) applications termed bubble Doppler is proposed and its feasibility tested in tissue-mimicking gel phantoms. pHIFU therapy uses short pulses, delivered at low pulse repetition frequency, to cause transient bubble activity that has been shown to enhance drug and gene delivery to tissues. The current gold standard for detecting and monitoring cavitation activity during pHIFU treatments is passive cavitation detection (PCD), which provides minimal information on the spatial distribution of the bubbles. B-mode imaging can detect hyperecho formation, but has very limited sensitivity, especially to small, transient microbubbles. The bubble Doppler method proposed here is based on a fusion of the adaptations of three Doppler techniques that had been previously developed for imaging of ultrasound contrast agents – color Doppler, pulse inversion Doppler, and decorrelation Doppler. Doppler ensemble pulses were interleaved with therapeutic pHIFU pulses using three different pulse sequences and standard Doppler processing was applied to the received echoes. The information yielded by each of the techniques on the distribution and characteristics of pHIFU-induced cavitation bubbles was evaluated separately, and found to be complementary. The unified approach - bubble Doppler – was then proposed to both spatially map the presence of transient bubbles and to estimate their sizes and the degree of nonlinearity. PMID:25265178

Bubble Augmented Propulsor Mixture Flow Simulation near Choked Flow Condition

NASA Astrophysics Data System (ADS)

Choi, Jin-Keun; Hsiao, Chao-Tsung; Chahine, Georges

2013-03-01

The concept of waterjet thrust augmentation through bubble injection has been the subject of many patents and publications over the past several decades, and computational and experimental evidences of the augmentation of the jet thrust through bubble growth in the jet stream have been reported. Through our experimental studies, we have demonstrated net thrust augmentation as high as 70%for air volume fractions as high as 50%. However, in order to enable practical designs, an adequately validated modeling tool is required. In our previous numerical studies, we developed and validated a numerical code to simulate and predict the performance of a two-phase flow water jet propulsion system for low void fractions. In the present work, we extend the numerical method to handle higher void fractions to enable simulations for the high thrust augmentation conditions. At high void fractions, the speed of sound in the bubbly mixture decreases substantially and could be as low as 20 m/s, and the mixture velocity can approach the speed of sound in the medium. In this numerical study, we extend our numerical model, which is based on the two-way coupling between the mixture flow field and Lagrangian tracking of a large number of bubbles, to accommodate compressible flow regimes. Numerical methods used and the validation studies for various flow conditions in the bubble augmented propulsor will be presented. This work is supported by Office of Naval Research through contract N00014-11-C-0482 monitored by Dr. Ki-Han Kim.

Hematology of healthy Florida manatees (Trichechus manatus)

USGS Publications Warehouse

Harvey, J.W.; Harr, K.E.; Murphy, D.; Walsh, M.T.; Nolan, E.C.; Bonde, R.K.; Pate, M.G.; Deutsch, C.J.; Edwards, H.H.; Clapp, W.L.

2009-01-01

Background: Hematologic analysis is an important tool in evaluating the general health status of free-ranging manatees and in the diagnosis and monitoring of rehabilitating animals. Objectives: The purpose of this study was to evaluate diagnostically important hematologic analytes in healthy manatees (Trichechus manatus) and to assess variations with respect to location (free ranging vs captive), age class (small calves, large calves, subadults, and adults), and gender. Methods: Blood was collected from 55 free-ranging and 63 captive healthy manatees. Most analytes were measured using a CELL-DYN 3500R; automated reticulocytes were measured with an ADVIA 120. Standard manual methods were used for differential leukocyte counts, reticulocyte and Heinz body counts, and plasma protein and fibrinogen concentrations. Results: Rouleaux, slight polychromasia, stomatocytosis, and low numbers of schistocytes and nucleated RBCs (NRBCs) were seen often in stained blood films. Manual reticulocyte counts were higher than automated reticulocyte counts. Heinz bodies were present in erythrocytes of most manatees. Compared with free-ranging manatees, captive animals had slightly lower MCV, MCH, and eosinophil counts and slightly higher heterophil and NRBC counts, and fibrinogen concentration. Total leukocyte, heterophil, and monocyte counts tended to be lower in adults than in younger animals. Small calves tended to have higher reticulocyte counts and NRBC counts than older animals. Conclusions: Hematologic findings were generally similar between captive and free-ranging manatees. Higher manual reticulocyte counts suggest the ADVIA detects only reticulocytes containing large amounts of RNA. Higher reticulocyte and NRBC counts in young calves probably reflect an increased rate of erythropoiesis compared with older animals. ?? 2009 American Society for Veterinary Clinical Pathology.

Helminth Fauna in Captive European Gray Wolves (Canis lupus lupus) in Germany.

PubMed

Bindke, Johanna Daniela; Springer, Andrea; Böer, Michael; Strube, Christina

2017-01-01

Captive as well as free-ranging wolves, which are currently recolonizing Germany, may harbor a variety of gastrointestinal parasites. This study investigated endoparasites in captive European gray wolves ( Canis lupus lupus ) using coproscopical methods. Fecal samples were collected monthly between October 2012 and November 2013 from 18 wolf enclosures in 14 German zoological gardens, representing 72 individual wolves. In total, 1,041 fecal samples including 26 bulk samples were analyzed by the sedimentation and flotation method. The most frequently detected egg morphotypes included five nematodes [Ancylostomatidae ( Ancylostoma or Uncinaria spp.), Toxocara canis, Toxascaris leonina, Trichuris vulpis , and Capillaria / Eucoleus spp.], one cestode (Taeniidae) and one trematode ( Alaria alata ). 44.76% of all samples were positive for at least one of these egg morphotypes. Overall, Ancylostomatidae showed the highest frequency (30.84% of all samples), followed by Capillaria/Eucoleus spp. (19.88%), Toxocara canis (5.19%), taeniids (3.75%), Trichuris vulpis and Alaria alata (3.65% each), and Toxascaris leonina (1.25%). As fecal samples were collected from the environment and could not be assigned to individual wolves, sample results were combined per zoo and month. General linear mixed models were employed to analyze the effect of season and management factors on the occurrence of Ancylostomatidae, Capillaria/Eucoleus spp., Toxocara canis and taeniids. No statistically significant effect of season was found, whereas anthelmintic treatment negatively affected Ancylostomatidae egg excretion. Detected parasites and their prevalences are comparable to previous studies on wolf parasitism conducted elsewhere in Europe. As many of the most prevalent helminths are of zoonotic importance, routine anthelmintic treatment of captive wolves should be recommended.

Real-time on-line ultrasonic monitoring for bubbles in ceramic 'slip' in pottery pipelines.

PubMed

Yim, Geun Tae; Leighton, Timothy G

2010-01-01

When casting ceramic items in potteries, liquid 'slip' is passed from a settling tank, through overhead pipelines, before being pumped manually into the moulds. It is not uncommon for bubbles to be introduced into the slip as it passes through the complex piping network, and indeed the presence of bubbles is a major source of financial loss to the ceramics industry worldwide. This is because the bubbles almost always remain undetected until after the ceramic items have been fired in a kiln, during which process bubbles expand and create unwanted holes in the pottery. Since there it is usually an interval of several hours between the injection of the slip into the moulds, and the inspection of the items after firing, such bubble generation goes undetected on the production line during the manufacture of hundreds or even thousands of ceramic units. Not only does this mean hours of wasted staff time, power consumption and production line time: the raw material which makes up these faulty items cannot even be recycled, as fired ceramic cannot be converted back into slip. Currently, the state-of-the-art method for detecting bubbles in the opaque ceramic slip is slow and invasive, can only be used off-line, and requires expertise which is rarely available. This paper describes the invention, engineering and in-factory testing across Europe of an ultrasonic system for real-time monitoring for the presence of bubbles in casting slip. It interprets changes in the scattering statistics accompanying the presence of the bubbles, the latter being detected through perturbations in the received signal when a narrow-band ultrasonic probing wave is transmitted through the slip. The device can be bolted onto the outside of the pipeline, or used in-line. It is automated, and requires no special expertise. The acoustic problems which had to be solved were severe, and included making the system capable of monitoring the slip regardless of the material of pipe (plastic, steel, etc.) and nature of the slip (which can be very variable). It must also be capable of detecting bubbles amongst the myriad solid particles and other species present in the flowing slip. The completed prototype was tested around several factories in Europe, and proved not only to be more versatile, but also more sensitive, than the state-of-the-art method.

Numerical and experimental study of dissociation in an air-water single-bubble sonoluminescence system.

PubMed

Puente, Gabriela F; Urteaga, Raúl; Bonetto, Fabián J

2005-10-01

We performed a comprehensive numerical and experimental analysis of dissociation effects in an air bubble in water acoustically levitated in a spherical resonator. Our numerical approach is based on suitable models for the different effects considered. We compared model predictions with experimental results obtained in our laboratory in the whole phase parameter space, for acoustic pressures from the bubble dissolution limit up to bubble extinction. The effects were taken into account simultaneously to consider the transition from nonsonoluminescence to sonoluminescence bubbles. The model includes (1) inside the bubble, transient and spatially nonuniform heat transfer using a collocation points method, dissociation of O2 and N2, and mass diffusion of vapor in the noncondensable gases; (2) at the bubble interface, nonequilibrium evaporation and condensation of water and a temperature jump due to the accommodation coefficient; (3) in the liquid, transient and spatially nonuniform heat transfer using a collocation points method, and mass diffusion of the gas in the liquid. The model is completed with a Rayleigh-Plesset equation with liquid compressible terms and vapor mass transfer. We computed the boundary for the shape instability based on the temporal evolution of the computed radius. The model is valid for an arbitrary number of dissociable gases dissolved in the liquid. We also obtained absolute measurements for R(t) using two photodetectors and Mie scattering calculations. The robust technique used allows the estimation of experimental results of absolute R0 and P(a). The technique is based on identifying the bubble dissolution limit coincident with the parametric instability in (P(a),R0) parameter space. We take advantage of the fact that this point can be determined experimentally with high precision and replicability. We computed the equilibrium concentration of the different gaseous species and water vapor during collapse as a function of P(a) and R0. The model obtains from first principles the result that in sonoluminescence the bubble is practically 100% argon for air dissolved in water. Therefore, the dissociation reactions in air bubbles must be taken into account for quantitative computations of maximum temperatures. The agreement found between the numerical and experimental data is very good in the whole parameter space explored. We do not fit any parameter in the model. We believe that we capture all the relevant physics with the model.

Hidden Attractors in a Model of a Bubble Contrast Agent Oscillating Near an Elastic Wall

NASA Astrophysics Data System (ADS)

Garashchuk, Ivan; Sinelshchikov, Dmitry; Kudryashov, Nikolay

2018-02-01

A model describing the dynamics of a spherical gas bubble in a compressible viscous liquid is studied. The bubble is oscillating close to an elastic wall of finite thickness under the influence of an external pressure field which simulates a contrast agent oscillating close to a blood vessel wall. Here we investigate numerically the coexistence of chaotic and periodic attractors in this model. One of the tools applied for seeking coexisting attractors is the perpetual points method. This method can be helpful for localizing coexisting attractors, occurring in various physically realistic ranges of variation of the control parameters. We provide some examples of coexisting attractors to demonstrate the importance of the multistability problem for the applications.

The structure of separated flow regions occurring near the leading edge of airfoils including transition

NASA Technical Reports Server (NTRS)

Mueller, T. J.

1986-01-01

A semi-empirical method for predicting separation bubble characteristics was evaluated using low Reynolds number test data. On the basis of this data, several observations were made. First, a sizable growth in the momentum thickness can occur in the laminar portion of a separation bubble. This is in direct contrast to the theory and is apparently due to low Reynolds number effects. Secondly, the transition Reynolds number (R sub l sub 1) which governs the extent of a bubble's laminar region, was found to be much lower than that used in the method. At present, there does not seem to be any evidence supporting a single value for R sub l sub 1. Apparently, R sub l sub 1 is affected by the freestream disturbance environment, and airfoil's pressure distribution, and possibly the chord Reynolds number as well. Thirdly, the growth in momentum thickness over a bubble's turbulent region was predicted reasonably well by the method, provided that Roberts' suggested value for the mean dissipation coefficient was used. Finally, the present data does not substantiate the universality of the velocity profile at reattachment. However, measurement error may be responsible for this result.

Bubble transport and sticking in gas embolotherapy

NASA Astrophysics Data System (ADS)

Bull, Joseph

2002-11-01

Pressure-driven bubble transport in a two-dimensional, bifurcating channel is investigated as a model of gas emboli transport in the microcirculation. Gas emboli are relevant to a number of clinical situations, and our particular interest is a novel gas embolotherapy technique, which involves using gas bubbles to occlude blood flow to tumors. This minimally invasive treatment modality allows selective delivery of emboli. The bubbles originate as 6 micron-diameter liquid droplets of perfluorocarbon (PFC), mixed in saline, and are injected into the vascular system. The droplet forms are small enough to pass through capillary beds, so they can circulate until the next stage of the therapy. By strategically placing an ultrasound source over the artery feeding the tumor, the droplets may be vaporized at that location. Our model is developed using the Stokes equation subject to interfacial and wall boundary conditions, and is solved using the boundary element method. The conditions under which bubbles 'stick' to the channel walls and occlude flow are investigated. Clinically, these results are important because the location and homogeneity of bubble sticking determines the degree of tumor necrosis and the efficacy of the treatment.

First Extended Catalogue of Galactic bubble infrared fluxes from WISE and Herschel surveys

NASA Astrophysics Data System (ADS)

Bufano, F.; Leto, P.; Carey, D.; Umana, G.; Buemi, C.; Ingallinera, A.; Bulpitt, A.; Cavallaro, F.; Riggi, S.; Trigilio, C.; Molinari, S.

2018-01-01

In this paper, we present the first extended catalogue of far-infrared fluxes of Galactic bubbles. Fluxes were estimated for 1814 bubbles, defined here as the 'golden sample', and were selected from the Milky Way Project First Data Release (Simpson et al.) The golden sample was comprised of bubbles identified within the Wide-field Infrared Survey Explorer (WISE) dataset (using 12- and 22-μm images) and Herschel data (using 70-, 160-, 250-, 350- and 500-μm wavelength images). Flux estimation was achieved initially via classical aperture photometry and then by an alternative image analysis algorithm that used active contours. The accuracy of the two methods was tested by comparing the estimated fluxes for a sample of bubbles, made up of 126 H II regions and 43 planetary nebulae, which were identified by Anderson et al. The results of this paper demonstrate that a good agreement between the two was found. This is by far the largest and most homogeneous catalogue of infrared fluxes measured for Galactic bubbles and it is a step towards the fully automated analysis of astronomical datasets.

Transient thermal driven bubble's surface and its potential ultrasound-induced damage

NASA Astrophysics Data System (ADS)

Movahed, Pooya; Freund, Jonathan B.

2017-11-01

Ultrasound-induced bubble activity in soft tissues is well-known to be a potential injury mechanism in therapeutic ultrasound treatments. We consider damage by transient thermal effects, including a hypothetical mechanism based on transient thermal phenomena, including viscous dissipation. A spherically symmetric compressible Navier-Stokes discretization is developed to solve the full governing equations, both inside and outside of the bubble, without the usual simplifications in the Rayleigh-Plesset bubble dynamics approach. Equations are solved in the Lagrangian framework, which provides a sharp and accurate representation of the interface as well as the viscous dissipation and thermal transport effects, which preclude reduction to the usual Rayleigh-Plesset ordinary differential equation. This method is used to study transient thermal effects at different frequencies and pressure amplitudes relevant to therapeutic ultrasound treatments. High temperatures achieved in the surrounding medium during the violent bubble collapse phase due to the viscous dissipation in the surrounding medium and thermal conduction from the bubble are expected to cause damage. This work was supported by NIH NIDDK Grant P01-DK043881.

Dynamic behaviors of cavitation bubble for the steady cavitating flow

NASA Astrophysics Data System (ADS)

Cai, Jun; Huai, Xiulan; Li, Xunfeng

2009-12-01

In this paper, by introducing the flow velocity item into the classical Rayleigh-Plesset dynamic equation, a new equation, which does not involve the time term and can describe the motion of cavitation bubble in the steady cavitating flow, has been obtained. By solving the new motion equation using Runge-Kutta fourth order method with adaptive step size control, the dynamic behaviors of cavitation bubble driven by the varying pressure field downstream of a venturi cavitation reactor are numerically simulated. The effects of liquid temperature (corresponding to the saturated vapor pressure of liquid), cavitation number and inlet pressure of venturi on radial motion of bubble and pressure pulse due to the radial motion are analyzed and discussed in detail. Some dynamic behaviors of bubble different from those in previous papers are displayed. In addition, the internal relationship between bubble dynamics and process intensification is also discussed. The simulation results reported in this work reveal the variation laws of cavitation intensity with the flow conditions of liquid, and will lay a foundation for the practical application of hydrodynamic cavitation technology.

On the origin of the driving force in the Marangoni propelled gas bubble trapping mechanism.

PubMed

Miniewicz, A; Quintard, C; Orlikowska, H; Bartkiewicz, S

2017-07-19

Gas bubbles can be trapped and then manipulated with laser light. In this report, we propose the detailed optical trapping mechanism of gas bubbles confined inside a thin light-absorbing liquid layer between two glass plates. The necessary condition of bubble trapping in this case is the direct absorption of light by the solution containing a dye. Due to heat release, fluid whirls propelled by the surface Marangoni effect at the liquid/gas interface emerge and extend to large distances. We report the experimental microscopic observation of the origin of whirls at an initially flat liquid/air interface as well as at the curved interface of a liquid/gas bubble and support this finding with advanced numerical simulations using the finite element method within the COMSOL Multiphysics platform. The simulation results were in good agreement with the observations, which allowed us to propose a simple physical model for this particular trapping mechanism, to establish the origin of forces attracting bubbles toward a laser beam and to predict other phenomena related to this effect.

Remobilizing the Interface of Thermocapillary Driven Bubbles Retarded By the Adsorption of a Surfactant Impurity on the Bubble Surface

NASA Technical Reports Server (NTRS)

Palaparthi, Ravi; Maldarelli, Charles; Papageorgiou, Dimitri; Singh, Bhim (Technical Monitor)

2001-01-01

Thermocapillary migration is a method for moving bubbles in space in the absence of buoyancy. A temperature gradient is the continuous phase in which a bubble is situated, and the applied gradient impressed on the bubble surface causes one pole of the drop to be cooler than the opposite pole. As the surface tension is a decreasing function of temperature, the cooler pole pulls at the warmer pole, creating a flow that propels the bubble in the direction of the warmer fluid. A major impediment to the practical use of thermocapillary to direct the movement of bubbles in space is the fact that surfactant impurities, which are unavoidably present in the continuous phase, can significantly reduce the migration velocity. A surfactant impurity adsorbed onto the bubble interface is swept to the trailing end of the bubble. When bulk concentrations are low (which is the case with an impurity), diffusion of surfactant to the front end is slow relative to convection, and surfactant collects at the back end of the bubble. Collection at the back lowers the surface tension relative to the front end setting up a reverse tension gradient. (This can also be the case if kinetic desorption of surfactant at the back end of the bubble is much slower than convection.) For buoyancy driven bubble motions in the absence of a thermocapillarity, the tension gradient opposes the surface flow, and reduces the surface and terminal velocities (the interface becomes more solid-like and bubbles translate as solid particles). When thermocapillary forces are present, the reverse tension gradient set up by the surfactant accumulation reduces the temperature-induced tension gradient, and can decrease to near zero the bubble's thermocapillary velocity. The objective of our research is to develop a method for enhancing the thermocapillary migration of bubbles which have be retarded by the adsorption onto the bubble surface of a surfactant impurity. Our remobilization theory proposes to use surfactant molecules which kinetically rapidly exchange between the bulk and the surface and are at high bulk concentrations. Because the remobilizing surfactant is present at much higher concentrations than the impurity, it adsorbs to the bubble surface much faster than the impurity when the bubble is formed, and thereby prevents the impurity from adsorbing onto the surface. In addition, the rapid kinetic exchange and high bulk concentration maintain a saturated surface with uniform surface concentrations. This prevents retarding surface tension gradients and keeps the thermocapillary velocity high. In our reports over the first 2 years, we presented numerical simulations of the bubble motion and surfactant transport which verified theoretically the concept of remobilization, and the development of an apparatus to track and measure the velocity of rising bubbles in a glycerol/water surfactant solution. This year, we detail experimental observations of remobilization. Two polyethylene oxide surfactants were studied, C12E6 (CH3(CH2)11(OCH2)6OH) and C10E8 (CH3(CH2)4(OCH2CH2)8OH). Measurements of the kinetic exchange for these surfactants show that the one with the longer hydrophobe chain C12E6 has a lower rate of kinetic exchange. In addition, this surfactant is much less soluble in the glycerol/water mixture because of the shorter ethoxylate chain. As a result, we found that C12E6 had only a very limited ability to remobilize rising bubbles because of the limited kinetic exchange and reduced solubility. However, C10E8, with its higher solubility and more rapid exchange was found to dramatically remobilize rising bubbles. We also compared our theoretical calculations to the experimental measurements of velocity for both the non-remobilizing and remobilizing surfactants and found excellent agreement. We further observed that for C10E8 at high concentrations, which exceeded the critical micelle concentrations, additional remobilization was measured. In this case the rapid exchange of monomer between micelle and surfactant provides an additional mechanism for maintaining a uniform surface concentrations.

Captive care and welfare considerations for beavers.

PubMed

Campbell-Palmer, Róisín; Rosell, Frank

2015-01-01

Beavers (Castor spp.) tend not to be a commonly held species and little published material exists relating to their captive care. We review published material and discuss husbandry issues taking into account the requirements of wild beavers. As social mammals with complex chemical communication systems and with such an ability to modify their environments, studies of wild counterparts suggest the captive requirements of beavers may actually be more sophisticated than generally perceived. Common field techniques may have practical application in the captive setting. Their widespread utilisation in conservation, including reintroductions, translocations and habitat management, also requires components of captive care. As welfare science advances there is increasing pressure on captive collections to improve standards and justify the keeping of animals. Conservation science is increasingly challenged to address individual welfare standards. Further research focusing on the captive care of beavers is required. © 2015 Wiley Periodicals, Inc.

Viscous decay of nonlinear oscillations of a spherical bubble at large Reynolds number

NASA Astrophysics Data System (ADS)

Smith, W. R.; Wang, Q. X.

2017-08-01

The long-time viscous decay of large-amplitude bubble oscillations is considered in an incompressible Newtonian fluid, based on the Rayleigh-Plesset equation. At large Reynolds numbers, this is a multi-scaled problem with a short time scale associated with inertial oscillation and a long time scale associated with viscous damping. A multi-scaled perturbation method is thus employed to solve the problem. The leading-order analytical solution of the bubble radius history is obtained to the Rayleigh-Plesset equation in a closed form including both viscous and surface tension effects. Some important formulae are derived including the following: the average energy loss rate of the bubble system during each cycle of oscillation, an explicit formula for the dependence of the oscillation frequency on the energy, and an implicit formula for the amplitude envelope of the bubble radius as a function of the energy. Our theory shows that the energy of the bubble system and the frequency of oscillation do not change on the inertial time scale at leading order, the energy loss rate on the long viscous time scale being inversely proportional to the Reynolds number. These asymptotic predictions remain valid during each cycle of oscillation whether or not compressibility effects are significant. A systematic parametric analysis is carried out using the above formula for the energy of the bubble system, frequency of oscillation, and minimum/maximum bubble radii in terms of the Reynolds number, the dimensionless initial pressure of the bubble gases, and the Weber number. Our results show that the frequency and the decay rate have substantial variations over the lifetime of a decaying oscillation. The results also reveal that large-amplitude bubble oscillations are very sensitive to small changes in the initial conditions through large changes in the phase shift.

'Blue bubble' technique: an ab interno approach for Descemet separation in deep anterior lamellar keratoplasty using trypan blue stained viscoelastic device.

PubMed

Livny, Eitan; Bahar, Irit; Hammel, Naama; Nahum, Yoav

2018-04-01

In this study, we examined a novel variant of 'big-bubble' deep anterior lamellar keratoplasty using trypan-blue-stained viscoelastic device for the creation of a pre-descemetic bubble. Ten corneoscleral rims were mounted on an artificial anterior chamber (AC). The AC was filled with air through a limbal paracentesis. A Melles' triangulated spatula was inserted through the paracentesis, with its tip penetrating the AC, was then slightly retracted and pushed into the deep stroma above the roof of the paracentesis. A mixture of trypan blue and viscoelastic device (Healon, Abbott Medical Optics, Abbott Park, Illinois) was injected into this intra-stromal pocket using a 27-G cannula to create a pre-descemetic separation bubble. Bubble type and visualization of dyed viscoelastic device were noted. The method was later employed in three cases. In all 10 corneoscleral rims, the technique successfully created a visible pre-descemetic (type 1) bubble that could be expanded up to the predicted diameter of trephination. Subsequent trephination and the removal of corneal stroma were uneventful. In two out of four clinical cases, a type 1 bubble was created, while in two others, visco-dissection failed and dyed viscoelastic was seen in the AC. The presented technique holds promise of being a relatively easy to perform, predictable and well-controlled alternative for achieving a type 1 bubble during deep anterior lamellar keratoplasty surgery. The trypan-blue-stained viscoelastic device facilitates proper visualization and control of the separation bubble and assists in identifying the penetrance to the separation bubble prior to removal of the stromal cap. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Numerical simulation of seismic wave propagation from land-excited large volume air-gun source

NASA Astrophysics Data System (ADS)

Cao, W.; Zhang, W.

2017-12-01

The land-excited large volume air-gun source can be used to study regional underground structures and to detect temporal velocity changes. The air-gun source is characterized by rich low frequency energy (from bubble oscillation, 2-8Hz) and high repeatability. It can be excited in rivers, reservoirs or man-made pool. Numerical simulation of the seismic wave propagation from the air-gun source helps to understand the energy partitioning and characteristics of the waveform records at stations. However, the effective energy recorded at a distance station is from the process of bubble oscillation, which can not be approximated by a single point source. We propose a method to simulate the seismic wave propagation from the land-excited large volume air-gun source by finite difference method. The process can be divided into three parts: bubble oscillation and source coupling, solid-fluid coupling and the propagation in the solid medium. For the first part, the wavelet of the bubble oscillation can be simulated by bubble model. We use wave injection method combining the bubble wavelet with elastic wave equation to achieve the source coupling. Then, the solid-fluid boundary condition is implemented along the water bottom. And the last part is the seismic wave propagation in the solid medium, which can be readily implemented by the finite difference method. Our method can get accuracy waveform of land-excited large volume air-gun source. Based on the above forward modeling technology, we analysis the effect of the excited P wave and the energy of converted S wave due to different water shapes. We study two land-excited large volume air-gun fields, one is Binchuan in Yunnan, and the other is Hutubi in Xinjiang. The station in Binchuan, Yunnan is located in a large irregular reservoir, the waveform records have a clear S wave. Nevertheless, the station in Hutubi, Xinjiang is located in a small man-made pool, the waveform records have very weak S wave. Better understanding of the characteristics of land-excited large volume air-gun can help to better use of the air-gun source.

Mycobacterium tuberculosis Infection among Asian Elephants in Captivity

PubMed Central

Simpson, Gary; Zimmerman, Ralph; Shashkina, Elena; Chen, Liang; Richard, Michael; Bradford, Carol M.; Dragoo, Gwen A.; Saiers, Rhonda L.; Peloquin, Charles A.; Daley, Charles L.; Planet, Paul; Narachenia, Apurva; Mathema, Barun

2017-01-01

Although awareness of tuberculosis among captive elephants is increasing, antituberculosis therapy for these animals is not standardized. We describe Mycobacterium tuberculosis transmission between captive elephants based on whole genome analysis and report a successful combination treatment. Infection control protocols and careful monitoring of treatment of captive elephants with tuberculosis are warranted. PMID:28221115

9 CFR 50.4 - Classification of cattle, bison, captive cervids, and other livestock as infected, exposed, or...

Code of Federal Regulations, 2010 CFR

2010-01-01

... AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF TUBERCULOSIS General..., or suspect. (a) Cattle, bison, and captive cervids are classified as infected with tuberculosis on... captive cervids are classified as exposed to tuberculosis when such cattle, bison, and captive cervids (1...

Activation of southern white rhinoceros (Ceratotherium simum simum) estrogen receptors by phytoestrogens and their potential role in thereproductive failure of captive-born females

EPA Science Inventory

The captive southern white rhinoceros (SWR; Ceratotherium simum simum) population serves as an important genetic reservoir critical to the conservation of this vulnerable species. Unfortunately, captive populations are declining due to the poor reproductive success of captive-bor...

9 CFR 50.4 - Classification of cattle, bison, captive cervids, and other livestock as infected, exposed, or...

Code of Federal Regulations, 2014 CFR

2014-01-01

... AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF TUBERCULOSIS General..., or suspect. (a) Cattle, bison, and captive cervids are classified as infected with tuberculosis on... captive cervids are classified as exposed to tuberculosis when such cattle, bison, and captive cervids (1...

9 CFR 50.4 - Classification of cattle, bison, captive cervids, and other livestock as infected, exposed, or...

Code of Federal Regulations, 2013 CFR

2013-01-01

... AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF TUBERCULOSIS General..., or suspect. (a) Cattle, bison, and captive cervids are classified as infected with tuberculosis on... captive cervids are classified as exposed to tuberculosis when such cattle, bison, and captive cervids (1...

9 CFR 50.4 - Classification of cattle, bison, captive cervids, and other livestock as infected, exposed, or...

Code of Federal Regulations, 2012 CFR

2012-01-01

... AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF TUBERCULOSIS General..., or suspect. (a) Cattle, bison, and captive cervids are classified as infected with tuberculosis on... captive cervids are classified as exposed to tuberculosis when such cattle, bison, and captive cervids (1...

9 CFR 50.4 - Classification of cattle, bison, captive cervids, and other livestock as infected, exposed, or...

Code of Federal Regulations, 2011 CFR

2011-01-01

... AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF TUBERCULOSIS General..., or suspect. (a) Cattle, bison, and captive cervids are classified as infected with tuberculosis on... captive cervids are classified as exposed to tuberculosis when such cattle, bison, and captive cervids (1...

The disadvantages of mating outside home: How breeding in captivity affects the reproductive success of seahorses?

NASA Astrophysics Data System (ADS)

Faleiro, Filipa; Narciso, Luís

2013-04-01

In captivity, husbandry conditions are distinct from those experienced by fish in the wild and may have a significant effect on reproductive success. This study evaluates the effect of supportive breeding (i.e., breeding animals in captivity using wild parents) on some quantitative and qualitative aspects of the reproductive success of the long-snouted seahorse, Hippocampus guttulatus. Wild and captive broods were compared in terms of juvenile number, size, condition and fatty acid profile at birth. Reproductive investment and breeding success of H. guttulatus decreased considerably in captivity. Juveniles from captive broods were fewer in number, smaller, generally thinner and with lower fatty acid contents (per juvenile) than those from wild broods, although their fatty acid composition (μg mg- 1 DW or %TFA) was not significantly affected. Although not greatly encouraging, the poor reproductive performance of captive seahorses should not, however, efface the potential of supportive breeding as a tool for seahorse conservation. Enhanced conditions and long-term breeding in captivity will allow to improve the reproductive success of the species and the quality of the fingerlings.

Experimental magma degassing: The revenge of the deformed bubbles

NASA Astrophysics Data System (ADS)

Marxer, H.; Bellucci, P.; Ulmer, S.; Nowak, M.

2013-12-01

We performed decompression experiments with a hydrated phonolitic melt at a T of 1323 K in an internally heated pressure vessel to investigate the effect of decompression method and rate on melt degassing. Samples were decompressed from 200 to 75 MPa with step-wise and continuous decompression (SD/CD) at nominal decompression rates (DRs) of 0.0028-1.7 MPa/s. At target P the samples were quenched rapidly under isobaric conditions with 150 K/s. The vesiculated glass products were compared in terms of bubble number density (BND), bubble size distribution (BSD) and residual H2O content. Almost all capsules were deformed after decompression: the initially crimped headspaces were expanded and the walls were inflexed in the capsule center. We postulate that the deformation is primarily due to the change in molar volume V(m) of exsolved H2O during rapid quench. Bubble growth in the melt contributes to the deformation by capsule expansion, but the main problem is the shrinkage and collapse of bubbles during cooling. In first approximation, the texture of the vesiculated melt is not frozen until the glass transition T (~773 K for this composition, [1]) is reached. From 1323 K to T(g) the melt will display viscous behavior. For a final P of 75 MPa, V(m) of the exsolved H2O at T(g) is only ~25% of V(m) at 1323 K [2]. The fluid P in the bubbles is therefore continuously decreasing during quench. In combination with constant external P, the bubbles can either contract isometrically, get deformed (flattened) or even become dented by sucking melt inwards, which can be observed in some glass products. The shrinkage of bigger bubbles in the capsules is sometimes affecting the whole vesicle texture in a sample. FPA-FTIR measurements did not reveal H2O diffusion profiles towards bubbles [3]. H2O concentration gradients around bubbles are expected to be disturbed or annihilated due to melt transport. All derived BSDs of our samples were corrected to resemble the bubble sizes prior to rapid quench. For a volumetric loss of 75% at a final P of 75 MPa, the initial diameter of a bubble in the melt has to be ~1.5x the diameter of a bubble in the glass. At DRs of >0.17 MPa/s the decompression method has only minor influence on melt degassing. SD and CD result in BNDs of 10^4-10^5 mm^-3. Fast P drop leads to immediate super-saturation with H2O in the melt. At high DRs, the diffusional transport of H2O is very limited and therefore bubble nucleation is the predominant degassing process. CD rates of ≤0.17 MPa/s provide sufficient time for H2O diffusion into existing bubbles. BNDs of CD samples with low DRs are several orders of magnitude lower than for SD experiments. In contrast to SD, bubble growth is the favored degassing mechanism. CD samples quenched at different target P at 0.024 MPa/s trace an equilibrium degassing path in terms of residual H2O content in the glass. SD techniques, as used in many studies before, are therefore not suitable to simulate melt degassing at continuous magma ascent. [1] Giordano, D; Russell, JK; Dingwell, DB; 2008. EPSL, 271: 123-134. [2] Duan, ZH; Zhang, ZG; 2006. GCA, 70: 2311-2324. [3] Marxer, H; Nowak, M; 2013. EJM, in press.

The use of α- or β-blockers to ameliorate the chronic stress of captivity in the house sparrow (Passer domesticus).

PubMed

Fischer, Clare Parker; Romero, L Michael

2016-01-01

When wild animals are brought into captivity for the first time, they frequently develop chronic stress symptoms. Animals can develop glucocorticoid dysregulation or changes in the sympathetic nervous system over the course of the first week in captivity. By blocking the action of epinephrine and norepinephrine using α- or β-blockers, we hoped to reduce the degree of chronic stress symptoms exhibited by newly captured house sparrows. We measured corticosterone, heart rate and heart rate variability in 24 house sparrows ( Passer domesticus ) over the first week of captivity. The birds were treated with saline, propranolol (a β-blocker) or phentolamine (an α-blocker) for the first 3 days of captivity. We also compared newly captured animals with animals that had been held in captivity for 1 month. During the first week of captivity, baseline corticosterone increased, but that increase was blocked by propranolol. Heart rate was not different between the treatment groups, but it was higher during the first week than after 1 month in captivity. Sympathetic nervous system activity (as measured by heart rate variability) decreased over the first week of captivity, but was not affected by treatment. β-Blockers, but not α-blockers, might help to improve some symptoms of chronic stress in newly captured animals.

Effects of captivity and artificial breeding on microbiota in feces of the red-crowned crane (Grus japonensis)

PubMed Central

Xie, Yuwei; Xia, Pu; Wang, Hui; Yu, Hongxia; Giesy, John P.; Zhang, Yimin; Mora, Miguel A.; Zhang, Xiaowei

2016-01-01

Reintroduction of the threatened red-crowned crane has been unsuccessful. Although gut microbiota correlates with host health, there is little information on gut microbiota of cranes under different conservation strategies. The study examined effects of captivity, artificial breeding and life stage on gut microbiota of red-crown cranes. The gut microbiotas of wild, captive adolescent, captive adult, artificially bred adolescent and artificially bred adult cranes were characterized by next-generation sequencing of 16S rRNA gene amplicons. The gut microbiotas were dominated by three phyla: Firmicutes (62.9%), Proteobacteria (29.9%) and Fusobacteria (9.6%). Bacilli dominated the ‘core’ community consisting of 198 operational taxonomic units (OTUs). Both captivity and artificial breeding influenced the structures and diversities microbiota of the gut. Especially, wild cranes had distinct compositions of gut microbiota from captive and artificially bred cranes. The greatest alpha diversity was found in captive cranes, while wild cranes had the least. According to the results of ordination analysis, influences of captivity and artificial breeding were greater than that of life stage. Overall, captivity and artificial breeding influenced the gut microbiota, potentially due to changes in diet, vaccination, antibiotics and living conditions. Metagenomics can serve as a supplementary non-invasive screening tool for disease control. PMID:27628212

Effects of captivity and artificial breeding on microbiota in feces of the red-crowned crane (Grus japonensis).

PubMed

Xie, Yuwei; Xia, Pu; Wang, Hui; Yu, Hongxia; Giesy, John P; Zhang, Yimin; Mora, Miguel A; Zhang, Xiaowei

2016-09-15

Reintroduction of the threatened red-crowned crane has been unsuccessful. Although gut microbiota correlates with host health, there is little information on gut microbiota of cranes under different conservation strategies. The study examined effects of captivity, artificial breeding and life stage on gut microbiota of red-crown cranes. The gut microbiotas of wild, captive adolescent, captive adult, artificially bred adolescent and artificially bred adult cranes were characterized by next-generation sequencing of 16S rRNA gene amplicons. The gut microbiotas were dominated by three phyla: Firmicutes (62.9%), Proteobacteria (29.9%) and Fusobacteria (9.6%). Bacilli dominated the 'core' community consisting of 198 operational taxonomic units (OTUs). Both captivity and artificial breeding influenced the structures and diversities microbiota of the gut. Especially, wild cranes had distinct compositions of gut microbiota from captive and artificially bred cranes. The greatest alpha diversity was found in captive cranes, while wild cranes had the least. According to the results of ordination analysis, influences of captivity and artificial breeding were greater than that of life stage. Overall, captivity and artificial breeding influenced the gut microbiota, potentially due to changes in diet, vaccination, antibiotics and living conditions. Metagenomics can serve as a supplementary non-invasive screening tool for disease control.

Comparisons of genetic diversity in captive versus wild populations of the federally endangered Quino checkerspot butterfly (Euphydryas editha quino Behr; Lepidoptera: Nymphalidae)

USGS Publications Warehouse

Miller, Mark P.; Pratt, Gordon F.; Mullins, Thomas D.; Haig, Susan M.

2014-01-01

Captive populations can play a significant role in threatened and endangered species management. An important consideration when developing and managing captive populations, however, is the maintenance of genetic diversity to ensure that adequate variation exists to avoid the negative consequences of inbreeding. In this investigation, we compared genetic diversity patterns within captive and wild populations of the federally endangered Quino checkerspot butterfly (Euphydryas editha quino Behr [Lepidoptera: Nymphalidae]), a taxon with a restricted distribution to chaparral and sage shrublands within Riverside and San Diego counties, California. Our analyses revealed that medium to high-frequency alleles from the wild populations were also present in the captive populations. While there was no significant difference in genetic diversity as quantified by expected heterozygosity, the captive populations showed tendencies toward significantly lower allelic richness than their wild counterparts. Given that alleles from the wild populations were occasionally not detected in captive populations, periodic incorporation of new wild specimens into the captive population would help ensure that allelic diversity is maintained to the extent possible. If performed in advance, genetic surveys of wild populations may provide the clearest insights regarding the number of individuals needed in captivity to adequately reflect wild populations.

Can sexual selection theory inform genetic management of captive populations? A review

PubMed Central

Chargé, Rémi; Teplitsky, Céline; Sorci, Gabriele; Low, Matthew

2014-01-01

Captive breeding for conservation purposes presents a serious practical challenge because several conflicting genetic processes (i.e., inbreeding depression, random genetic drift and genetic adaptation to captivity) need to be managed in concert to maximize captive population persistence and reintroduction success probability. Because current genetic management is often only partly successful in achieving these goals, it has been suggested that management insights may be found in sexual selection theory (in particular, female mate choice). We review the theoretical and empirical literature and consider how female mate choice might influence captive breeding in the context of current genetic guidelines for different sexual selection theories (i.e., direct benefits, good genes, compatible genes, sexy sons). We show that while mate choice shows promise as a tool in captive breeding under certain conditions, for most species, there is currently too little theoretical and empirical evidence to provide any clear guidelines that would guarantee positive fitness outcomes and avoid conflicts with other genetic goals. The application of female mate choice to captive breeding is in its infancy and requires a goal-oriented framework based on the needs of captive species management, so researchers can make honest assessments of the costs and benefits of such an approach, using simulations, model species and captive animal data. PMID:25553072

Numerical study on the splitting of a vapor bubble in the ultrasonic assisted EDM process with the curved tool and workpiece.

PubMed

Shervani-Tabar, M T; Seyed-Sadjadi, M H; Shabgard, M R

2013-01-01

Electrical discharge machining (EDM) is a powerful and modern method of machining. In the EDM process, a vapor bubble is generated between the tool and the workpiece in the dielectric liquid due to an electrical discharge. In this process dynamic behavior of the vapor bubble affects machining process. Vibration of the tool surface affects bubble behavior and consequently affects material removal rate (MRR). In this paper, dynamic behavior of the vapor bubble in an ultrasonic assisted EDM process after the appearance of the necking phenomenon is investigated. It is noteworthy that necking phenomenon occurs when the bubble takes the shape of an hour-glass. After the appearance of the necking phenomenon, the vapor bubble splits into two parts and two liquid jets are developed on the boundaries of the upper and lower parts of the vapor bubble. The liquid jet developed on the upper part of the bubble impinges to the tool and the liquid jet developed on the lower part of the bubble impinges to the workpiece. These liquid jets cause evacuation of debris from the gap between the tool and the workpiece and also cause erosion of the workpiece and the tool. Curved tool and workpiece affect the shape and the velocity of the liquid jets during splitting of the vapor bubble. In this paper dynamics of the vapor bubble after its splitting near the curved tool and workpiece is investigated in three cases. In the first case surfaces of the tool and the workpiece are flat, in the second case surfaces of the tool and the workpiece are convex and in the third case surfaces of the tool and workpiece are concave. Numerical results show that in the third case, the velocity of liquid jets which are developed on the boundaries of the upper and lower parts of the vapor bubble after its splitting have the highest magnitude and their shape are broader than the other cases. Copyright © 2012 Elsevier B.V. All rights reserved.

Derivation of nonlinear wave equations for ultrasound beam in nonuniform bubbly liquids

NASA Astrophysics Data System (ADS)

Kanagawa, Tetsuya; Yano, Takeru; Kawahara, Junya; Kobayashi, Kazumichi; Watanabe, Masao; Fujikawa, Shigeo

2012-09-01

Weakly nonlinear propagation of diffracted ultrasound beams in a nonuniform bubbly liquid is theoretically studied based on the method of multiple scales with the set of scaling relations of some physical parameters. It is assumed that the spatial distribution of the number density of bubbles in an initial state at rest is a slowly varying function of space coordinates and the amplitude of its variation is small compared with a mean number density. As a result, a Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation with dispersion and nonuniform effects for a low frequency case and a nonlinear Schrödinger (NLS) equation with dissipation, diffraction, and nonuniform effects for a high frequency case, are derived from the basic equations of bubbly flows.

Modes of self-organization of diluted bubbly liquids in acoustic fields: One-dimensional theory.

PubMed

Gumerov, Nail A; Akhatov, Iskander S

2017-02-01

The paper is dedicated to mathematical modeling of self-organization of bubbly liquids in acoustic fields. A continuum model describing the two-way interaction of diluted polydisperse bubbly liquids and acoustic fields in weakly-nonlinear approximation is studied analytically and numerically in the one-dimensional case. It is shown that the regimes of self-organization of monodisperse bubbly liquids can be controlled by only a few dimensionless parameters. Two basic modes, clustering and propagating shock waves of void fraction (acoustically induced transparency), are identified and criteria for their realization in the space of parameters are proposed. A numerical method for solving of one-dimensional self-organization problems is developed. Computational results for mono- and polydisperse systems are discussed.

Photothermal generation of microbubbles on plasmonic nanostructures inside microfluidic channels

NASA Astrophysics Data System (ADS)

Li, Jingting; Li, Ming; Santos, Greggy M.; Zhao, Fusheng; Shih, Wei-Chuan

2016-03-01

Microbubbles have been utilized as micro-pumps, micro-mixers, micro-valves, micro-robots and surface cleaners. Various generation techniques can be found in the literature, including resistive heating, hydrodynamic methods, illuminating patterned metal films and noble metal nanoparticles of Au or Ag. We present photothermal microbubble generation by irradiating nanoporous gold disk covered microfluidic channels. The size of the microbubble can be controlled by adjusting the laser power. The dynamics of both bubble growth and shrinkage are studied. The advantages of this technique are flexible bubble generation locations, long bubble lifetimes, no need for light-adsorbing dyes, high controllability over bubble size, low power consumption, etc. This technique has the potential to provide new flow control functions in microfluidic devices.

Theoretical and Experimental Investigation of Particle Trapping via Acoustic Bubbles

NASA Astrophysics Data System (ADS)

Chen, Yun; Fang, Zecong; Merritt, Brett; Saadat-Moghaddam, Darius; Strack, Dillon; Xu, Jie; Lee, Sungyon

2014-11-01

One important application of lab-on-a-chip devices is the trapping and sorting of micro-objects, with acoustic bubbles emerging as an effective, non-contact method. Acoustically actuated bubbles are known to exert a secondary radiation force on micro-particles and trap them, when this radiation force exceeds the drag force that acts to keep the particles in motion. In this study, we theoretically evaluate the magnitudes of these two forces for varying actuation frequencies and voltages. In particular, the secondary radiation force is calculated directly from bubble oscillation shapes that have been experimentally measured for varying acoustic parameters. Finally, based on the force estimates, we predict the threshold voltage and frequency for trapping and compare them to the experimental results.

Sterilization Effect of Wet Oxygen Plasma in the Bubbling Method.

PubMed

Tamazawa, Kaoru; Shintani, Hideharu; Tamazawa, Yoshinori; Shimauchi, Hidetoshi

2015-01-01

A new low-temperature sterilization method to replace the ethylene oxide gas sterilization is needed. Strong bactericidal effects of OH and O2H radicals are well known. The purpose of this study was to evaluate the sterilization effect of wet oxygen ("O2+H2O") plasma in the bubbling method, confirming the effect of humidity. Sterility assurance was confirmed by using a biological indicator (Geobacillus stearothermophilus ATCC7953, Namsa, USA). One hundred and eight samples (10(5) spores/carrier) were divided into three groups of 36 in each for treatment with a different type of gas (O2, O2+H2O, Air+H2O). Plasma processing was conducted using a plasma ashing apparatus (13.56 MHz, PACK-3(®), Y. A. C., Japan) under various gas pressures (13, 25, 50 Pa) and gas flows (50, 100, 200 sccm). Fixed plasma treatment parameters were power at 150 W, temperature of 60 ℃, treatment time of 10 min. The samples after treatment were incubated in trypticase soy broth at 58 ℃ for 72 h. The negative culture rate in the "O2+H2O" group was significantly (Mantel-Haenszel procedure, p<0.001) higher than in the other gas groups. It is suggested that the significant sterilization effect of the "O2+H2O" group depends on the bubbling method which is the method of introducing vapor into the chamber. The bubbling method seems able to generate OH and O2H radicals in a stable way.

Modified Right Heart Contrast Echocardiography Versus Traditional Method in Diagnosis of Right-to-Left Shunt: A Comparative Study.

PubMed

Wang, Yi; Zeng, Jie; Yin, Lixue; Zhang, Mei; Hou, Dailun

2016-01-01

The purpose of this study was to evaluate the reliability, effectiveness, and safety of modified right heart contrast transthoracic echocardiography (cTTE) in comparison with the traditional method. We performed a modified right heart cTTE using saline mixed with a small sample of patient's own blood. Samples were agitated with varying intensity. This study protocol involved microscopic analysis and patient evaluation. 1. Microscopic analysis: After two contrast samples had been agitated 10 or 20 times, they underwent a comparison of bubble size, bubble number, and red blood cell morphology. 2. Patient analysis: 40 patients with suspected RLS (right- to-left shunt) were enrolled. All patients underwent right heart contrast echocardiography. Oxygen saturation, transit time and duration, presence of RLS, change in indirect bilirubin and urobilinogen concentrations were compared afterward. Modified method generated more bubbles (P<0.05), but the differences in bubble size were not significant (P>0.05). Twenty-four patients were diagnosed with RLS (60%) using the modified method compared to 16 patients (40%) with the traditional method. The transit time of ASb20 group was the shortest (P<0.05). However, the duration time in this group was much longer (P<0.05). Also, in semi-quantitative analysis mean rank of RLS was higher after injecting the modified contrast agent agitated 20 times (P<0.05). Modified right heart contrast echocardiography is a reliable, effective and safe method of detecting cardiovascular RLS.

How well can captive breeding programs conserve biodiversity? A review of salmonids

PubMed Central

Fraser, Dylan J

2008-01-01

Captive breeding programs are increasingly being initiated to prevent the imminent extinction of endangered species and/or populations. But how well can they conserve genetic diversity and fitness, or re-establish self-sustaining populations in the wild? A review of these complex questions and related issues in salmonid fishes reveals several insights and uncertainties. Most programs can maintain genetic diversity within populations over several generations, but available research suggests the loss of fitness in captivity can be rapid, its magnitude probably increasing with the duration in captivity. Over the long-term, there is likely tremendous variation between (i) programs in their capacity to maintain genetic diversity and fitness, and (ii) species or even intraspecific life-history types in both the severity and manner of fitness-costs accrued. Encouragingly, many new theoretical and methodological approaches now exist for current and future programs to potentially reduce these effects. Nevertheless, an unavoidable trade-off exists between conserving genetic diversity and fitness in certain instances, such as when captive-bred individuals are temporarily released into the wild. Owing to several confounding factors, there is also currently little evidence that captive-bred lines of salmonids can or cannot be reintroduced as self-sustaining populations. Most notably, the root causes of salmonid declines have not been mitigated where captive breeding programs exist. Little research has also addressed under what conditions an increase in population abundance due to captive-rearing might offset fitness reductions induced in captivity. Finally, more empirical investigation is needed to evaluate the genetic/fitness benefits and risks associated with (i) maintaining captive broodstocks as either single or multiple populations within one or more facilities, (ii) utilizing cryopreservation or surrogate broodstock technologies, and (iii) adopting other alternatives to captive-rearing such as translocations to new habitats. Management recommendations surrounding these issues are proposed, with the aim of facilitating meta-analyses and more general principles or guidelines for captive-breeding. These include the need for the following: (i) captive monitoring to involve, a priori, greater application of hypothesis testing through the use of well-designed experiments and (ii) improved documentation of procedures adopted by specific programs for reducing the loss of genetic diversity and fitness. PMID:25567798

The Effects of Captivity on the Mammalian Gut Microbiome.

PubMed

McKenzie, Valerie J; Song, Se Jin; Delsuc, Frédéric; Prest, Tiffany L; Oliverio, Angela M; Korpita, Timothy M; Alexiev, Alexandra; Amato, Katherine R; Metcalf, Jessica L; Kowalewski, Martin; Avenant, Nico L; Link, Andres; Di Fiore, Anthony; Seguin-Orlando, Andaine; Feh, Claudia; Orlando, Ludovic; Mendelson, Joseph R; Sanders, Jon; Knight, Rob

2017-10-01

Recent studies increasingly note the effect of captivity or the built environment on the microbiome of humans and other animals. As symbiotic microbes are essential to many aspects of biology (e.g., digestive and immune functions), it is important to understand how lifestyle differences can impact the microbiome, and, consequently, the health of hosts. Animals living in captivity experience a range of changes that may influence the gut bacteria, such as diet changes, treatments, and reduced contact with other individuals, species and variable environmental substrates that act as sources of bacterial diversity. Thus far, initial results from previous studies point to a pattern of decreased bacterial diversity in captive animals. However, these studies are relatively limited in the scope of species that have been examined. Here we present a dataset that includes paired wild and captive samples from mammalian taxa across six Orders to investigate generalizable patterns of the effects captivity on mammalian gut bacteria. In comparing the wild to the captive condition, our results indicate that alpha diversity of the gut bacteria remains consistent in some mammalian hosts (bovids, giraffes, anteaters, and aardvarks), declines in the captive condition in some hosts (canids, primates, and equids), and increases in the captive condition in one host taxon (rhinoceros). Differences in gut bacterial beta diversity between the captive and wild state were observed for most of the taxa surveyed, except the even-toed ungulates (bovids and giraffes). Additionally, beta diversity variation was also strongly influenced by host taxonomic group, diet type, and gut fermentation physiology. Bacterial taxa that demonstrated larger shifts in relative abundance between the captive and wild states included members of the Firmicutes and Bacteroidetes. Overall, the patterns that we observe will inform a range of disciplines from veterinary practice to captive breeding efforts for biological conservation. Furthermore, bacterial taxa that persist in the captive state provide unique insight into symbiotic relationships with the host. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Social network and dominance hierarchy analyses at Chimpanzee Sanctuary Northwest

PubMed Central

Mayhew, Jessica A.; Mulcahy, John B.

2018-01-01

Different aspects of sociality bear considerable weight on the individual- and group-level welfare of captive nonhuman primates. Social Network Analysis (SNA) is a useful tool for gaining a holistic understanding of the dynamic social relationships of captive primate groups. Gaining a greater understanding of captive chimpanzees through investigations of centrality, preferred and avoided relationships, dominance hierarchy, and social network diagrams can be useful in advising current management practices in sanctuaries and other captive settings. In this study, we investigated the dyadic social relationships, group-level social networks, and dominance hierarchy of seven chimpanzees (Pan troglodytes) at Chimpanzee Sanctuary Northwest. We used focal-animal and instantaneous scan sampling to collect 106.75 total hours of associative, affiliative, and agonistic data from June to September 2016. We analyzed our data using SOCPROG to derive dominance hierarchies and network statistics, and we diagrammed the group’s social networks in NetDraw. Three individuals were most central in the grooming network, while two others had little connection. Through agonistic networks, we found that group members reciprocally exhibited agonism, and the group’s dominance hierarchy was statistically non-linear. One chimpanzee emerged as the most dominant through agonism but was least connected to other group members across affiliative networks. Our results indicate that the conventional methods used to calculate individuals’ dominance rank may be inadequate to wholly depict a group’s social relationships in captive sanctuary populations. Our results have an applied component that can aid sanctuary staff in a variety of ways to best ensure the improvement of group welfare. PMID:29444112

Social network and dominance hierarchy analyses at Chimpanzee Sanctuary Northwest.

PubMed

Funkhouser, Jake A; Mayhew, Jessica A; Mulcahy, John B

2018-01-01

Different aspects of sociality bear considerable weight on the individual- and group-level welfare of captive nonhuman primates. Social Network Analysis (SNA) is a useful tool for gaining a holistic understanding of the dynamic social relationships of captive primate groups. Gaining a greater understanding of captive chimpanzees through investigations of centrality, preferred and avoided relationships, dominance hierarchy, and social network diagrams can be useful in advising current management practices in sanctuaries and other captive settings. In this study, we investigated the dyadic social relationships, group-level social networks, and dominance hierarchy of seven chimpanzees (Pan troglodytes) at Chimpanzee Sanctuary Northwest. We used focal-animal and instantaneous scan sampling to collect 106.75 total hours of associative, affiliative, and agonistic data from June to September 2016. We analyzed our data using SOCPROG to derive dominance hierarchies and network statistics, and we diagrammed the group's social networks in NetDraw. Three individuals were most central in the grooming network, while two others had little connection. Through agonistic networks, we found that group members reciprocally exhibited agonism, and the group's dominance hierarchy was statistically non-linear. One chimpanzee emerged as the most dominant through agonism but was least connected to other group members across affiliative networks. Our results indicate that the conventional methods used to calculate individuals' dominance rank may be inadequate to wholly depict a group's social relationships in captive sanctuary populations. Our results have an applied component that can aid sanctuary staff in a variety of ways to best ensure the improvement of group welfare.

Hydrophobically-associating cationic polymers as micro-bubble surface modifiers in dissolved air flotation for cyanobacteria cell separation.

PubMed

Yap, R K L; Whittaker, M; Diao, M; Stuetz, R M; Jefferson, B; Bulmus, V; Peirson, W L; Nguyen, A V; Henderson, R K

2014-09-15

Dissolved air flotation (DAF), an effective treatment method for clarifying algae/cyanobacteria-laden water, is highly dependent on coagulation-flocculation. Treatment of algae can be problematic due to unpredictable coagulant demand during blooms. To eliminate the need for coagulation-flocculation, the use of commercial polymers or surfactants to alter bubble charge in DAF has shown potential, termed the PosiDAF process. When using surfactants, poor removal was obtained but good bubble adherence was observed. Conversely, when using polymers, effective cell removal was obtained, attributed to polymer bridging, but polymers did not adhere well to the bubble surface, resulting in a cationic clarified effluent that was indicative of high polymer concentrations. In order to combine the attributes of both polymers (bridging ability) and surfactants (hydrophobicity), in this study, a commercially-available cationic polymer, poly(dimethylaminoethyl methacrylate) (polyDMAEMA), was functionalised with hydrophobic pendant groups of various carbon chain lengths to improve adherence of polymer to a bubble surface. Its performance in PosiDAF was contrasted against commercially-available poly(diallyl dimethyl ammonium chloride) (polyDADMAC). All synthesised polymers used for bubble surface modification were found to produce positively charged bubbles. When applying these cationic micro-bubbles in PosiDAF, in the absence of coagulation-flocculation, cell removals in excess of 90% were obtained, reaching a maximum of 99% cell removal and thus demonstrating process viability. Of the synthesised polymers, the polymer containing the largest hydrophobic functionality resulted in highly anionic treated effluent, suggesting stronger adherence of polymers to bubble surfaces and reduced residual polymer concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Simulation and analysis of collapsing vapor-bubble clusters with special emphasis on potentially erosive impact loads at walls

NASA Astrophysics Data System (ADS)

Ogloblina, Daria; Schmidt, Steffen J.; Adams, Nikolaus A.

2018-06-01

Cavitation is a process where a liquid evaporates due to a pressure drop and re-condenses violently. Noise, material erosion and altered system dynamics characterize for such a process for which shock waves, rarefaction waves and vapor generation are typical phenomena. The current paper presents novel results for collapsing vapour-bubble clusters in a liquid environment close to a wall obtained by computational fluid mechanics (CFD) simulations. The driving pressure initially is 10 MPa in the liquid. Computations are carried out by using a fully compressible single-fluid flow model in combination with a conservative finite volume method (FVM). The investigated bubble clusters (referred to as "clouds") differ by their initial vapor volume fractions, initial stand-off distances to the wall and by initial bubble radii. The effects of collapse focusing due to bubble-bubble interaction are analysed by investigating the intensities and positions of individual bubble collapses, as well as by the resulting shock-induced pressure field at the wall. Stronger interaction of the bubbles leads to an intensification of the collapse strength for individual bubbles, collapse focusing towards the center of the cloud and enhanced re-evaporation. The obtained results reveal collapse features which are common for all cases, as well as case-specific differences during collapse-rebound cycles. Simultaneous measurements of maximum pressures at the wall and within the flow field and of the vapor volume evolution show that not only the primary collapse but also subsequent collapses are potentially relevant for erosion.

Bubble dynamics in microchannels: inertial and capillary migration forces

NASA Astrophysics Data System (ADS)

Rivero-Rodriguez, Javier; Scheid, Benoit

2018-05-01

This work focuses on the dynamics of a train of unconfined bubbles flowing in microchan- nels. We investigate the transverse position of a train of bubbles, its velocity and the associated pressure drop when flowing in a microchannel depending on the internal forces due to viscosity, inertia and capillarity. Despite the small scales of the system, inertia, referred to as inertial migration force, play a crucial role in determining the transverse equilibrium position of the bubbles. Beside inertia and viscosity, other effects may also affect the transverse migration of bubbles such as the Marangoni surface stresses and the surface deformability. We look at the influence of surfactants in the limit of infinite Marangoni effect which yields rigid bubble interface. The resulting migration force may balance external body forces if present such as buoyancy, Dean or magnetic ones. This balance not only determines the transverse position of the bubbles but, consequently, the surrounding flow structure, which can be determinant for any mass/heat transfer process involved. Finally, we look at the influence of the bubble deformation on the equilibrium position and compare it to the inertial migration force at the centred position, explaining the stable or unstable character of this position accordingly. A systematic study of the influence of the parameters - such as the bubble size, uniform body force, Reynolds and capillary numbers - has been carried out using numerical simulations based on the Finite Element Method, solving the full steady Navier-Stokes equations and its asymptotic counterpart for the limits of small Reynolds and/or capillary numbers.

Liter-scale production of uniform gas bubbles via parallelization of flow-focusing generators.

PubMed

Jeong, Heon-Ho; Yadavali, Sagar; Issadore, David; Lee, Daeyeon

2017-07-25

Microscale gas bubbles have demonstrated enormous utility as versatile templates for the synthesis of functional materials in medicine, ultra-lightweight materials and acoustic metamaterials. In many of these applications, high uniformity of the size of the gas bubbles is critical to achieve the desired properties and functionality. While microfluidics have been used with success to create gas bubbles that have a uniformity not achievable using conventional methods, the inherently low volumetric flow rate of microfluidics has limited its use in most applications. Parallelization of liquid droplet generators, in which many droplet generators are incorporated onto a single chip, has shown great promise for the large scale production of monodisperse liquid emulsion droplets. However, the scale-up of monodisperse gas bubbles using such an approach has remained a challenge because of possible coupling between parallel bubbles generators and feedback effects from the downstream channels. In this report, we systematically investigate the effect of factors such as viscosity of the continuous phase, capillary number, and gas pressure as well as the channel uniformity on the size distribution of gas bubbles in a parallelized microfluidic device. We show that, by optimizing the flow conditions, a device with 400 parallel flow focusing generators on a footprint of 5 × 5 cm 2 can be used to generate gas bubbles with a coefficient of variation of less than 5% at a production rate of approximately 1 L h -1 . Our results suggest that the optimization of flow conditions using a device with a small number (e.g., 8) of parallel FFGs can facilitate large-scale bubble production.

Acoustic trapping in bubble-bounded micro-cavities

NASA Astrophysics Data System (ADS)

O'Mahoney, P.; McDougall, C.; Glynne-Jones, P.; MacDonald, M. P.

2016-12-01

We present a method for controllably producing longitudinal acoustic trapping sites inside microfluidic channels. Air bubbles are injected into a micro-capillary to create bubble-bounded `micro-cavities'. A cavity mode is formed that shows controlled longitudinal acoustic trapping between the two air/water interfaces along with the levitation to the centre of the channel that one would expect from a lower order lateral mode. 7 μm and 10 μm microspheres are trapped at the discrete acoustic trapping sites in these micro-cavities.We show this for several lengths of micro-cavity.

50 CFR 15.31 - Criteria for including species in the approved list for captive-bred species.

Code of Federal Regulations, 2012 CFR

2012-10-01

... approved list for captive-bred species. 15.31 Section 15.31 Wildlife and Fisheries UNITED STATES FISH AND..., EXPORTATION, AND IMPORTATION OF WILDLIFE AND PLANTS WILD BIRD CONSERVATION ACT Approved List of Species Listed... captive-bred species. The Director will periodically review the list of captive-bred exotic bird species...

50 CFR 15.31 - Criteria for including species in the approved list for captive-bred species.

Code of Federal Regulations, 2014 CFR

2014-10-01

... approved list for captive-bred species. 15.31 Section 15.31 Wildlife and Fisheries UNITED STATES FISH AND..., EXPORTATION, AND IMPORTATION OF WILDLIFE AND PLANTS WILD BIRD CONSERVATION ACT Approved List of Species Listed... captive-bred species. The Director will periodically review the list of captive-bred exotic bird species...

50 CFR 15.31 - Criteria for including species in the approved list for captive-bred species.

Code of Federal Regulations, 2011 CFR

2011-10-01

... approved list for captive-bred species. 15.31 Section 15.31 Wildlife and Fisheries UNITED STATES FISH AND..., EXPORTATION, AND IMPORTATION OF WILDLIFE AND PLANTS WILD BIRD CONSERVATION ACT Approved List of Species Listed... captive-bred species. The Director will periodically review the list of captive-bred exotic bird species...

50 CFR 15.31 - Criteria for including species in the approved list for captive-bred species.

Code of Federal Regulations, 2013 CFR

2013-10-01

... approved list for captive-bred species. 15.31 Section 15.31 Wildlife and Fisheries UNITED STATES FISH AND..., EXPORTATION, AND IMPORTATION OF WILDLIFE AND PLANTS WILD BIRD CONSERVATION ACT Approved List of Species Listed... captive-bred species. The Director will periodically review the list of captive-bred exotic bird species...

50 CFR 15.31 - Criteria for including species in the approved list for captive-bred species.

Code of Federal Regulations, 2010 CFR

2010-10-01

... approved list for captive-bred species. 15.31 Section 15.31 Wildlife and Fisheries UNITED STATES FISH AND..., EXPORTATION, AND IMPORTATION OF WILDLIFE AND PLANTS WILD BIRD CONSERVATION ACT Approved List of Species Listed... captive-bred species. The Director will periodically review the list of captive-bred exotic bird species...

Captivate Your Audience by Turning Powerpoint Presentations into Interactive E-Learning Content

ERIC Educational Resources Information Center

Young, Montessa; Hirnyck, Ronda; Agenbroad, Ariel; Bechinski, Edward J.

2015-01-01

Adobe® Captivate software provides educators with a tool to create interactive distance learning modules. This article describes how Adobe® Captivate was used to increase engagement of volunteer learners. An Adobe® Captivate module was created for the University of Idaho Master Gardener program to educate and test new Master Gardener volunteers on…

A method to assess relative preference for training and environmental enrichment in captive wolves (Canis lupus and Canis lupus arctos).

PubMed

Dorey, Nicole R; Mehrkam, Lindsay R; Tacey, Jay

2015-11-01

It is currently debated as to whether or not positive reinforcement training is enriching to captive animals. Although both husbandry training and environmental enrichment (EE) have been found to benefit animal welfare in captivity, to date, no systematic investigation has compared an animal's preference for performing a trained behavior to engaging freely with a stimuli provided as EE. In the current paper, we used four captive wolves to (1) test the efficacy of a paired-stimulus preference assessment to determine preference for engaging in a trained behavior as a choice; and to (2) use a paired-stimulus preference assessment to determine whether or not individuals prefer to engage in a previously trained behavior versus a previously encountered EE stimuli. Of the four subjects tested, visual inspection of the graphs revealed that two of the subjects preferred trained behavior stimuli and two of the subjects preferred EE stimuli; only one of the wolves had a statically higher preference for an EE stimulus over a trained behavior. We believe that letting the animals choose between these two events is the first step in answering the question of whether or not is training enriching, however more research needs to be done and suggestions for future research is discussed. © 2015 Wiley Periodicals, Inc.

A super-resolution ultrasound method for brain vascular mapping

PubMed Central

O'Reilly, Meaghan A.; Hynynen, Kullervo

2013-01-01

Purpose: High-resolution vascular imaging has not been achieved in the brain due to limitations of current clinical imaging modalities. The authors present a method for transcranial ultrasound imaging of single micrometer-size bubbles within a tube phantom. Methods: Emissions from single bubbles within a tube phantom were mapped through an ex vivo human skull using a sparse hemispherical receiver array and a passive beamforming algorithm. Noninvasive phase and amplitude correction techniques were applied to compensate for the aberrating effects of the skull bone. The positions of the individual bubbles were estimated beyond the diffraction limit of ultrasound to produce a super-resolution image of the tube phantom, which was compared with microcomputed tomography (micro-CT). Results: The resulting super-resolution ultrasound image is comparable to results obtained via the micro-CT for small tissue specimen imaging. Conclusions: This method provides superior resolution to deep-tissue contrast ultrasound and has the potential to be extended to provide complete vascular network imaging in the brain. PMID:24320408

Gastrointestinal parasites of owls (Strigiformes) kept in captivity in the Southern region of Brazil.

PubMed

da Silva, Aleksandro S; Zanette, Régis A; Lara, Valéria M; Gressler, Luciane T; Carregaro, Adriano B; Santurio, Janio M; Monteiro, Silvia G

2009-01-01

The aim of this research was to study the gastrointestinal parasitism in 12 adult owls kept in captivity in the Southern region of Brazil. Cloacal contents of the species Rhinoptynx clamator, Tyto alba, Athene cunicularia, Megascops spp., and Bubo virginianus were evaluated. Feces and urine were collected and analyzed by the zinc sulfate centrifugal-flotation method and stained by the modified Ziehl-Neelsen technique. Eggs of Capillaria spp. and Strongylida, oocysts of Cryptosporidium spp., Eimeria spp., and Isospora spp. were observed. The birds showed no clinical signs, probably due to the mild nature of the infection.

Are captive tortoises a reservoir for conservation? An assessment of genealogical affiliation of captive Gopherus agassizii to local, wild populations

USGS Publications Warehouse

Berry, Kristin H.; Edwards, Taylor

2013-01-01

The conservation of tortoises poses a unique situation because several threatened species are commonly kept as pets within their native ranges. Thus, there is potential for captive populations to be a reservoir for repatriation efforts. We assess the utility of captive populations of the threatened Agassiz’s desert tortoise (Gopherus agassizii) for recovery efforts based on genetic affinity to local areas. We collected samples from 130 captive desert tortoises from three desert communities: two in California (Ridgecrest and Joshua Tree) and the Desert Tortoise Conservation Center (Las Vegas) in Nevada. We tested all samples for 25 short tandem repeats and sequenced 1,109 bp of the mitochondrial genome. We compared captive genotypes to a database of 1,258 Gopherus samples, including 657 wild caught G. agassizii spanning the full range of the species. We conducted population assignment tests to determine the genetic origins of the captive individuals. For our total sample set, only 44 % of captive individuals were assigned to local populations based on genetic units derived from the reference database. One individual from Joshua Tree, California, was identified as being a Morafka’s desert tortoise, G. morafkai, a cryptic species which is not native to the Mojave Desert. Our data suggest that captive desert tortoises kept within the native range of G. agassizii cannot be presumed to have a genealogical affiliation to wild tortoises in their geographic proximity. Precautions should be taken before considering the release of captive tortoises into the wild as a management tool for recovery.

The use of α- or β-blockers to ameliorate the chronic stress of captivity in the house sparrow (Passer domesticus)

PubMed Central

Fischer, Clare Parker; Romero, L. Michael

2016-01-01

When wild animals are brought into captivity for the first time, they frequently develop chronic stress symptoms. Animals can develop glucocorticoid dysregulation or changes in the sympathetic nervous system over the course of the first week in captivity. By blocking the action of epinephrine and norepinephrine using α- or β-blockers, we hoped to reduce the degree of chronic stress symptoms exhibited by newly captured house sparrows. We measured corticosterone, heart rate and heart rate variability in 24 house sparrows (Passer domesticus) over the first week of captivity. The birds were treated with saline, propranolol (a β-blocker) or phentolamine (an α-blocker) for the first 3 days of captivity. We also compared newly captured animals with animals that had been held in captivity for 1 month. During the first week of captivity, baseline corticosterone increased, but that increase was blocked by propranolol. Heart rate was not different between the treatment groups, but it was higher during the first week than after 1 month in captivity. Sympathetic nervous system activity (as measured by heart rate variability) decreased over the first week of captivity, but was not affected by treatment. β-Blockers, but not α-blockers, might help to improve some symptoms of chronic stress in newly captured animals. PMID:27752321

77 FR 58084 - Endangered and Threatened Wildlife and Plants; 90-Day Findings on Petitions To Delist U.S...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-19

...-0077; 4500030115] Endangered and Threatened Wildlife and Plants; 90-Day Findings on Petitions To Delist... to remove the U.S. captive-bred and U.S. captive populations of three antelope species, the scimitar... delisting the U.S. captive animals or U.S. captive-bred members of these species may be warranted. Therefore...

Genetic diversity and sex ratio of naked mole rat, Heterocephalus glaber, zoo populations.

PubMed

Chau, Linh M; Groh, Amy M; Anderson, Emily C; Alcala, Micaela O; Mendelson, Joseph R; Slade, Stephanie B; Kerns, Kenton; Sarro, Steve; Lusardi, Clinton; Goodisman, Michael A D

2018-05-01

The naked mole rat, Heterocephalus glaber, is a highly unusual mammal that displays a complex social system similar to that found in eusocial insects. Colonies of H. glaber are commonly maintained in zoo collections because they represent fascinating educational exhibits for the public. However, little is known about the genetic structure or sex ratio of captive populations of H. glaber. In this study, we developed a set of microsatellite markers to examine genetic variation in three captive zoo populations of H. glaber. We also studied sex ratio of these captive populations. Our goal was to determine levels of genetic variation within, and genetic differences between, captive populations of H. glaber. Overall, we found modest levels of genetic variation in zoo populations. We also uncovered little evidence for inbreeding within the captive populations. However, zoo populations did differ genetically, which may reflect the isolation of captive naked mole rat colonies. Finally, we found no evidence of biased sex ratios within colonies. Overall, our study documents levels of genetic variation and sex ratios in a captive eusocial mammalian population. Our results may provide insight into how to manage captive populations of H. glaber. © 2018 Wiley Periodicals, Inc.

Intraluminal bubble dynamics induced by lithotripsy shock wave

NASA Astrophysics Data System (ADS)

Song, Jie; Bai, Jiaming; Zhou, Yufeng

2016-12-01

Extracorporeal shock wave lithotripsy (ESWL) has been the first option in the treatment of calculi in the upper urinary tract since its introduction. ESWL-induced renal injury is also found after treatment and is assumed to associate with intraluminal bubble dynamics. To further understand the interaction of bubble expansion and collapse with the vessel wall, the finite element method (FEM) was used to simulate intraluminal bubble dynamics and calculate the distribution of stress in the vessel wall and surrounding soft tissue during cavitation. The effects of peak pressure, vessel size, and stiffness of soft tissue were investigated. Significant dilation on the vessel wall occurs after contacting with rapid and large bubble expansion, and then vessel deformation propagates in the axial direction. During bubble collapse, large shear stress is found to be applied to the vessel wall at a clinical lithotripter setting (i.e. 40 MPa peak pressure), which may be the mechanism of ESWL-induced vessel rupture. The decrease of vessel size and viscosity of soft tissue would enhance vessel deformation and, consequently, increase the generated shear stress and normal stresses. Meanwhile, a significantly asymmetric bubble boundary is also found due to faster axial bubble expansion and shrinkage than in radial direction, and deformation of the vessel wall may result in the formation of microjets in the axial direction. Therefore, this numerical work would illustrate the mechanism of ESWL-induced tissue injury in order to develop appropriate counteractive strategies for reduced adverse effects.

Method for enhancing selectivity and recovery in the fractional flotation of particles in a flotation column

DOEpatents

Klunder, Edgar B [Bethel Park, PA

2011-08-09

The method relates to particle separation from a feed stream. The feed stream is injected directly into the froth zone of a vertical flotation column in the presence of a counter-current reflux stream. A froth breaker generates a reflux stream and a concentrate stream, and the reflux stream is injected into the froth zone to mix with the interstitial liquid between bubbles in the froth zone. Counter-current flow between the plurality of bubbles and the interstitial liquid facilitates the attachment of higher hydrophobicity particles to bubble surfaces as lower hydrophobicity particles detach. The height of the feed stream injection and the reflux ratio may be varied in order to optimize the concentrate or tailing stream recoveries desired based on existing operating conditions.

9 CFR 77.30 - Nonaccredited States or zones.

Code of Federal Regulations, 2010 CFR

2010-01-01

... AGRICULTURE INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TUBERCULOSIS Captive... “Uniform Methods and Rules—Bovine Tuberculosis Eradication” and that tuberculosis is prevalent in less than...

9 CFR 77.30 - Nonaccredited States or zones.

Code of Federal Regulations, 2012 CFR

2012-01-01

... AGRICULTURE INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TUBERCULOSIS Captive... “Uniform Methods and Rules—Bovine Tuberculosis Eradication” and that tuberculosis is prevalent in less than...

9 CFR 77.30 - Nonaccredited States or zones.

Code of Federal Regulations, 2011 CFR

2011-01-01

... AGRICULTURE INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TUBERCULOSIS Captive... “Uniform Methods and Rules—Bovine Tuberculosis Eradication” and that tuberculosis is prevalent in less than...

9 CFR 77.30 - Nonaccredited States or zones.

Code of Federal Regulations, 2014 CFR

2014-01-01

... AGRICULTURE INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TUBERCULOSIS Captive... “Uniform Methods and Rules—Bovine Tuberculosis Eradication” and that tuberculosis is prevalent in less than...

9 CFR 77.30 - Nonaccredited States or zones.

Code of Federal Regulations, 2013 CFR

2013-01-01

... AGRICULTURE INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TUBERCULOSIS Captive... “Uniform Methods and Rules—Bovine Tuberculosis Eradication” and that tuberculosis is prevalent in less than...

Sperm cryopreservation in endangered felids: developing linkage of in situ-ex situ populations.

PubMed

Swanson, W F; Magarey, G M; Herrick, J R

2007-01-01

Many of the world's cat species face growing threats to their continued survival in nature. For some species, managed captive populations may provide a reservoir for future reintroduction or genetic augmentation. Because most zoo populations are derived from small founder sizes and are subject to loss of genetic variation over time, periodic infusion of founder alleles is necessary to avoid the dire consequences of inbreeding. Collection and freezing of semen from free-living nondomestic felids offers a viable option for introducing founder genes into captive populations without removal of animals from the wild. The effective application of this strategy requires established protocols for safely capturing and anaesthetising wild cats coupled with suitable methods of semen recovery, processing and cryopreservation under field conditions. In small-sized non-domestic felids, the general feasibility of this approach is being explored in two studies of black-footed cats and Pallas' cats. Two factors - relatively low sperm numbers per ejaculate and compromised status of frozen-thawed cat spermatozoa - suggest that in vitro fertilisation (IVF) and embryo transfer present the most efficient use of this limiting resource in small-sized cats. Our studies with captive felids have explored alternative methods of sperm cryopreservation that are adaptable to field situations and shown that frozen-thawed spermatozoa from Pallas' cats, ocelots, and fishing cats exhibit adequate function to fertilise heterologous and/or homologous oocytes in vitro. Most recently, we investigated the fertilising capacity of frozen-thawed spermatozoa obtained from wild Pallas' cats in Mongolia. Combined with improved methods for embryo culture and transfer in small cat species, sperm banking in situ will facilitate introduction of new founders into captive populations without causing further depletion of their wild counterparts. As one component of holistic conservation programs, including ongoing support of field ecology studies in range countries, this reproductive strategy serves to further strengthen linkages among imperiled ex situ and in situ cat populations.

Influence of grid resolution, parcel size and drag models on bubbling fluidized bed simulation

DOE PAGES

Lu, Liqiang; Konan, Arthur; Benyahia, Sofiane

2017-06-02

Here in this paper, a bubbling fluidized bed is simulated with different numerical parameters, such as grid resolution and parcel size. We examined also the effect of using two homogeneous drag correlations and a heterogeneous drag based on the energy minimization method. A fast and reliable bubble detection algorithm was developed based on the connected component labeling. The radial and axial solids volume fraction profiles are compared with experiment data and previous simulation results. These results show a significant influence of drag models on bubble size and voidage distributions and a much less dependence on numerical parameters. With a heterogeneousmore » drag model that accounts for sub-scale structures, the void fraction in the bubbling fluidized bed can be well captured with coarse grid and large computation parcels. Refining the CFD grid and reducing the parcel size can improve the simulation results but with a large increase in computation cost.« less

Effects of the kinematic viscosity and surface tension on the bubble take-off period in a catalase-hydrogen peroxide system.

PubMed

Sasaki, Satoshi; Iida, Yoshinori

2009-06-01

The effect of kinematic viscosity and surface tension of the solution was investigated by adding catalase, glucose oxidase, or glucose on the bubble movement in a catalase-hydrogen peroxide system. The kinematic viscosity was measured using a Cannon-Fenske kinematic viscometer. The surface tension of the solution was measured by the Wilhelmy method using a self-made apparatus. The effects of the hole diameter/cell wall thickness, catalase concentration, glucose concentration, and glucose oxidase concentration on the kinematic viscosity, surface tension, and bubble take-off period were investigated. With our system, the effects of the changes in the solution materiality on the bubble take-off period were proven to be very small in comparison to the change in the oxygen-producing rate.

Acoustic bubble sorting for ultrasound contrast agent enrichment.

PubMed

Segers, Tim; Versluis, Michel

2014-05-21

An ultrasound contrast agent (UCA) suspension contains encapsulated microbubbles with a wide size distribution, with radii ranging from 1 to 10 μm. Medical transducers typically operate at a single frequency, therefore only a small selection of bubbles will resonate to the driving ultrasound pulse. Thus, the sensitivity can be improved by narrowing down the size distribution. Here, we present a simple lab-on-a-chip method to sort the population of microbubbles on-chip using a traveling ultrasound wave. First, we explore the physical parameter space of acoustic bubble sorting using well-defined bubble sizes formed in a flow-focusing device, then we demonstrate successful acoustic sorting of a commercial UCA. This novel sorting strategy may lead to an overall improvement of the sensitivity of contrast ultrasound by more than 10 dB.

Effective in vitro and in vivo gene delivery by the combination of liposomal bubbles (bubble liposomes) and ultrasound exposure.

PubMed

Suzuki, Ryo; Maruyama, Kazuo

2010-01-01

Gene delivery with a physical mechanism using ultrasound (US) and nano/microbubbles is expected as an ideal system in terms of delivering plasmid DNA noninvasively into a specific target site. We developed novel liposomal bubbles (Bubble liposomes (BLs)) containing the lipid nanobubbles of perfluoropropane which were utilized for contrast enhancement in ultrasonography. BLs were smaller in diameter than conventional microbubbles and induced cavitation upon exposure ultrasound. In addition, when coupled with US exposure, BLs could deliver plasmid DNA into various types of cells in vitro and in vivo. The transfection efficiency with BLs and US was higher than that with conventional lipofection method. Therefore, the combination of BLs and US might be an efficient and novel nonviral gene delivery system.

Physiochemical properties and reproducibility of air-based sodium tetradecyl sulphate foam using the Tessari method.

PubMed

Watkins, Mike R; Oliver, Richard J

2017-07-01

Objectives The objectives were to examine the density, bubble size distribution and durability of sodium tetradecyl sulphate foam and the consistency of production of foam by a number of different operators using the Tessari method. Methods 1% and 3% sodium tetradecyl sulphate sclerosant foam was produced by an experienced operator and a group of inexperienced operators using either a 1:3 or 1:4 liquid:air ratio and the Tessari method. The foam density, bubble size distribution and foam durability were measured on freshly prepared foam from each operator. Results The foam density measurements were similar for each of the 1:3 preparations and for each of the 1:4 preparations but not affected by the sclerosant concentration. The bubble size for all preparations were very small immediately after preparation but progressively coalesced to become a micro-foam (<250 µm) after the first 30 s up until 2 min. Both the 1% and 3% solution foams developed liquid more rapidly when made in a 1:3 ratio (37 s) than in a 1:4 ratio (45 s) but all combinations took similar times to reach 0.4 ml liquid formation. For all the experiments, there was no statistical significant difference between operators. Conclusions The Tessari method of foam production for sodium tetradecyl sulphate sclerosant is consistent and reproducible even when made by inexperienced operators. The best quality foam with micro bubbles should be used within the first minute after production.

Sonic wave separation of invertase from a dilute solution to generated droplets.

PubMed

Tanner, R D; Ko, S; Loha, V; Prokop, A

2000-01-01

It has previously been shown that a droplet fractionation process, simulated by shaking a separatory funnel containing a dilute protein solution, can generate droplets richer in protein than present in the original dilute solution. In this article, we describe an alternative method that can increase the amount of protein transferred to the droplets. The new method uses ultrasonic waves, enhanced by a bubble gas stream to create the droplets. The amount of protein in these droplets increases by about 50%. In this method, the top layer of the dilute protein solution (of the solution-air interface) becomes enriched in protein when air is bubbled into the solution. This concentrating procedure is called bubble fractionation. Once the protein has passed through the initial buildup, this enriched protein layer is transferred into droplets with the aid of a vacuum above the solution at the same time that ultrasonic waves are introduced. The droplets are then carried over to a condenser and coalesced. We found that this new method provides an easier way to remove the protein-enriched top layer of the dilute solution and generates more droplets within a shorter period than the separatory funnel droplet generation method. The added air creates the bubbles and carries the droplets, and the vacuum helps remove the effluent airstream from the condenser. The maximum partition coefficient, the ratio of the protein concentration in the droplets to that in the residual solution (approx 8.5), occurred at pH 5.0.

Colorimetric-Solid Phase Extraction Technology for Water Quality Monitoring: Evaluation of C-SPE and Debubbling Methods in Microgravity

NASA Technical Reports Server (NTRS)

Hazen-Bosveld, April; Lipert, Robert J.; Nordling, John; Shih, Chien-Ju; Siperko, Lorraine; Porter, Marc D.; Gazda, Daniel B.; Rutz, Jeff A.; Straub, John E.; Schultz, John R.;

Numerical simulation of a bubble rising in an environment consisting of Xanthan gum

NASA Astrophysics Data System (ADS)

Aguirre, Víctor A.; Castillo, Byron A.; Narvaez, Christian P.

2017-09-01

An improved numerical algorithm for front tracking method is developed to simulate a bubble rising in viscous liquid. In the new numerical algorithm, volume correction is introduced to conserve the bubble volume while tracking the bubble's rising and deforming. Volume flux conservation is adopted to solve the Navier-Stokes equation for fluid flow using finite volume method. Non-Newtonian fluids are widely used in industry such as feed and energy industries. In this research we used Xanthan gum which is a microbiological polysaccharide. In order to obtain the properties of the Xanthan gum, such as viscosity, storage and loss modulus, shear rate, etc., it was necessary to do an amplitude sweep and steady flow test in a rheometer with a concentric cylinder as geometry. Based on the data given and using a numerical regression, the coefficients required by Giesekus model are obtained. With these coefficients, it is possible to simulate the comportment of the fluid by the use of the developed algorithm. Once the data given by OpenFOAM is acquired, it is compared with the experimental data.

Free fatty acids degradation in grease trap purification using ozone bubbling and sonication

NASA Astrophysics Data System (ADS)

Piotr Kwiatkowski, Michal; Satoh, Saburoh; Fukuda, Shogo; Yamabe, Chobei; Ihara, Satoshi; Nieda, Masanori

2013-02-01

The oil and fat were treated at first by only ozone bubbling and it was confirmed that the collection efficiency of them became 98.4% when the aeration was used. It showed that the aeration method in a grease trap cleared the standard value of 90% and there was no worry on the oil and fat outflow from a grease trap. The characteristics of sonication process were studied for free fatty acids degradation. The free saturated fatty acids are the most hard-degradable compounds of the fats, oils and greases (FOGs) in the grease trap. The influence of various parameters such as immersion level of an ultrasound probe in the liquid and bubbling of various gases (Ar, O2, air, O3) on the sonochemical and energy efficiency of the sonication process was investigated. The most effective degradation treatment method for saturated free fatty acids was the combination of sonication and low flow rate argon bubbling. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

Estimation of structural film viscosity based on the bubble rise method in a nanofluid.

PubMed

Cho, Heon Ki; Nikolov, Alex D; Wasan, Darsh T

2018-04-15

When a single bubble moves at a very low capillary number (10 -7 ) through a liquid with dispersed nanoparticles (nanofluid) inside a vertical tube/capillary, a film is formed between the bubble surface and the tube wall and the nanoparticles self-layer inside the confined film. We measured the film thickness using reflected light interferometry. We calculated the film structural energy isotherm vs. the film thickness from the film-meniscus contact angle measurements using the reflected light interferometric method. Based on the experimental measurement of the film thickness and the calculated values of the film structural energy barrier, we estimated the structural film viscosity vs. the film thickness using the Frenkel approach. Because of the nanoparticle film self-layering phenomenon, we observed a gradual increase in the film viscosity with the decreasing film thickness. However, we observed a significant increase in the film viscosity accompanied by a step-wise decrease in the bubble velocity when the film thickness decreased from 3 to 2 particle layers due to the structural transition in the film. Copyright © 2018 Elsevier Inc. All rights reserved.

Preparation and characterization of a novel silicon-modified nanobubble

PubMed Central

Li, Maotong; Zhou, Meijun; Li, Fei; Huang, Xiuxian; Pan, Min; Xue, Li

2017-01-01

Nanobubbles (NBs) opened a new field of ultrasound imaging. There is still no practical method to control the diameter of bubbles. In this study, we developed a new method to control the size by incorporating of silicon hybrid lipids into the bubble membrane. The range of particle size of resulting NBs is between 523.02 ± 46.45 to 857.18 ± 82.90, smaller than the conventional microbubbles. The size of resulting NBs increased with the decrease in amount of silicon hybrid lipids, indicating the diameter of NBs can be regulated through modulating the ratio of silicon hybrid lipids in the bubble shell. Typical harmonic signals could be detected. The in vitro and in vivo ultrasound imaging experiments demonstrated these silicon-modified NBs had significantly improved ultrasound contrast enhancement abilities. Cytotoxicity assays revealed that these NBs had no obvious cytotoxicity to the 293 cell line at the tested bubble concentration. Our results showed that the novel NBs could use as nanoscale ultrasound contrast agents, providing the foundation for NBs in future applications including contrast-enhanced imaging and drug/gene delivery. PMID:28557995

The effects of automated scatter feeders on captive grizzly bear activity budgets.

PubMed

Andrews, Nathan L P; Ha, James C

2014-01-01

Although captive bears are popular zoo attractions, they are known to exhibit high levels of repetitive behaviors (RBs). These behaviors have also made them particularly popular subjects for welfare research. To date, most research on ursid welfare has focused on various feeding methods that seek to increase time spent searching for, extracting, or consuming food. Prior research indicates an average of a 50% reduction in RBs when attempts are successful and, roughly, a 50% success rate across studies. This research focused on decreasing time spent in an RB while increasing the time spent active by increasing time spent searching for, extracting, and consuming food. The utility of timed, automated scatter feeders was examined for use with captive grizzly bears (Ursis arctos horribilis). Findings include a significant decrease in time spent in RB and a significant increase in time spent active while the feeders were in use. Further, the bears exhibited a wider range of behaviors and a greater use of their enclosure.

Evidence for chronic stress in captive but not free-ranging cheetahs (Acinonyx jubatus) based on adrenal morphology and function.

PubMed

Terio, Karen A; Marker, Laurie; Munson, Linda

2004-04-01

The cheetah (Acinonyx jubatus) is highly endangered because of loss of habitat in the wild and failure to thrive in captivity. Cheetahs in zoos reproduce poorly and have high prevalences of unusual diseases that cause morbidity and mortality. These diseases are rarely observed in free-ranging cheetahs but have been documented in cheetahs that have been captured and held in captive settings either temporarily or permanently. Because captivity may be stressful for this species and stress is suspected as contributing to poor health and reproduction, this study aimed to measure chronic stress by comparing baseline concentrations of fecal corticoid metabolites and adrenal gland morphology between captive and free-ranging cheetahs. Additionally, concentrations of estradiol and testosterone metabolites were quantified to determine whether concentrations of gonadal steroids correlated with corticoid concentration and to assure that corticosteroids in the free-ranging samples were not altered by environmental conditions. Concetntrations of fecal corticoids, estradiol, and testosterone were quantified by radioimmunoassay in 20 free-ranging and 20 captive cheetahs from samples collected between 1994 and 1999. Concentrations of baseline fecal corticoids were significantly higher (p = 0.005) in captive cheetahs (196.08 +/- 36.20 ng/g dry feces) than free-ranging cheetahs (71.40 +/- 14.35 ng/g dry feces). Testosterone concentrations were lower in captive male cheetahs (9.09 +/- 2.84 ng/g dry feces) than in free-ranging cheetahs (34.52 +/- 12.11 ng/g dry feces), which suggests suppression by elevated corticoids in the captive males. Evidence for similar sulppression of estradiol concentrations in females was not present. Adrenal corticomedullary ratios were determined on midsagittal sections of adrenal glands from 13 free-ranging and 13 captive cheetahs obtained between 1991 and 2002. The degree of vacuolation of cortical cells in the zona fasciculata was graded for each animal. Corticomedullary ratios were larger (p = 0.05) in captive cheetahs; however, there was no difference (p = 0.31) in the degree of corticocyte vacnolation between the two populations. These data proxile both mnorphologic and functional evidence suggestive of chronic stress in captive cheetahs. Further research into the role of hypercortisolemia in the pathogenesis of the reproductive abnormalities and unusual diseases of captive cheetahs is needed.

Antioxidant activities of nano-bubble hydrogen-dissolved water assessed by ESR and 2,2'-bipyridyl methods.

PubMed

Kato, Shinya; Matsuoka, Daigo; Miwa, Nobuhiko

2015-08-01

We prepared nano-bubble hydrogen-dissolved water (nano-H water) which contained hydrogen nano-bubbles of <717-nm diameter for 54% of total bubbles. In the DMPO-spin trap electron spin resonance (ESR) method, the DMPO-OH:MnO ratio, being attributed to amounts of hydroxyl radicals (OH), was 2.78 for pure water (dissolved hydrogen [DH]≤0.01 ppm, oxidation-reduction potential [ORP]=+324 mV), 2.73 for tap water (0.01 ppm, +286 mV), 2.93 for commercially available hydrogen water (0.075 ppm, +49 mV), and 2.66 for manufactured hydrogen water (0.788 ppm, -614 mV), whereas the nano-H water (0.678 ppm, -644 mV) exhibited 2.05, showing the superiority of nano-H water to other types of hydrogen water in terms of OH-scavenging activity. Then, the reduction activity of nano-H water was assessed spectrophotometrically by the 2,2'-bipyridyl method. Differential absorbance at 530 nm was in the order: 0.018 for pure water, 0.055 for tap water, 0.079 for nano-H water, 0.085 for commercially available hydrogen water, and 0.090 for manufactured hydrogen water, indicating a prominent reduction activity of hydrogen water and nano-H water against oxidation in ascorbate-coupled ferric ion-bipyridyl reaction. Thus, nano-H water has an improved antioxidant activity as compared to hydrogen water of similar DH-level, indicating the more marked importance of nano-bubbles rather than the concentration of hydrogen in terms of OH-scavenging. Copyright © 2015 Elsevier B.V. All rights reserved.

Informative frame detection from wireless capsule video endoscopic images

NASA Astrophysics Data System (ADS)

Bashar, Md. Khayrul; Mori, Kensaku; Suenaga, Yasuhito; Kitasaka, Takayuki; Mekada, Yoshito

2008-03-01

Wireless capsule endoscopy (WCE) is a new clinical technology permitting the visualization of the small bowel, the most difficult segment of the digestive tract. The major drawback of this technology is the high amount of time for video diagnosis. In this study, we propose a method for informative frame detection by isolating useless frames that are substantially covered by turbid fluids or their contamination with other materials, e.g., faecal, semi-processed or unabsorbed foods etc. Such materials and fluids present a wide range of colors, from brown to yellow, and/or bubble-like texture patterns. The detection scheme, therefore, consists of two stages: highly contaminated non-bubbled (HCN) frame detection and significantly bubbled (SB) frame detection. Local color moments in the Ohta color space are used to characterize HCN frames, which are isolated by the Support Vector Machine (SVM) classifier in Stage-1. The rest of the frames go to the Stage-2, where Laguerre gauss Circular Harmonic Functions (LG-CHFs) extract the characteristics of the bubble-structures in a multi-resolution framework. An automatic segmentation method is designed to extract the bubbled regions based on local absolute energies of the CHF responses, derived from the grayscale version of the original color image. Final detection of the informative frames is obtained by using threshold operation on the extracted regions. An experiment with 20,558 frames from the three videos shows the excellent average detection accuracy (96.75%) by the proposed method, when compared with the Gabor based- (74.29%) and discrete wavelet based features (62.21%).

Mechanisms of thrombolysis acceleration by cavitation

NASA Astrophysics Data System (ADS)

Weiss, Hope; Selvaraj, Prashanth; Ahadi, Golnaz; Voie, Arne; Hoelscher, Thilo; Okita, Kohei; Matsumoto, Yoichiro; Szeri, Andrew

2012-11-01

Recent studies, in vitro and in vivo, have shown that High Intensity Focused Ultrasound (HIFU) accelerates thrombolysis, the dissolution of blood clots, for ischemic stroke. Although the mechanisms are not fully understood, cavitation is thought to play an important role in sonothrombolysis. The damage to a blood clot's fibrin fiber network from cavitation in a HIFU field is studied using two independent approaches for an embedded bubble. One method is extended to the more important scenario of a bubble outside a blood clot that collapses asymmetrically creating a jet towards the clot. There is significantly more damage potential from a bubble undergoing cavitation collapse outside the clot compared to a rapidly expanding bubble embedded within the clot structure. Also, the effects of the physical properties of skull bone when a HIFU wave propagates through it are examined by use of computer simulation. The dynamics of a test bubble placed at the focus is used in understanding of the pressure field. All other things being equal, the analysis suggests that skull thickness can alter the wave at the focus, which in turn can change the nature of cavitation bubble dynamics and the amount of energy available for clot damage. Now at MSOE.

Effects of Soluble Surfactant on Lateral Migration of a Bubble in a Shear Flow

NASA Astrophysics Data System (ADS)

Muradoglu, Metin; Tryggvason, Gretar

2014-11-01

Motivated by the recent experimental study of Takagi et al. (2008), direct numerical simulations are performed to examine effects of soluble surfactant on the lateral migration of a deformable bubble in a pressure-driven channel flow. The interfacial and bulk surfactant concentration evolution equations are solved fully coupled with the incompressible Navier-Stokes equations. A non-linear equation of state is used to relate interfacial surface tension to surfactant concentration at the interface. A multiscale method is developed to handle the mass exchange between the interface and bulk fluid at high Peclet numbers, using a boundary-layer approximation next to the bubble and a relatively coarse grid for the rest of the flow. It is found that the surfactant induced Marangoni stresses can dominate over the shear-induced lift force and thus alter the behavior of the bubble completely, i.e., the contaminated bubble drifts away from the channel wall and stabilizes at the center of the channel in contrast with the corresponding clean bubble that drifts toward the wall and stabilizes near the wall. The Scientific and Technical Research Council of Turkey (TUBITAK), Grant 112M181 and Turkish Academy of Sciences (TUBA).

A system for measuring bubble voidage and frequency around tubes immersed in a fluidized bed of particles

NASA Astrophysics Data System (ADS)

Whitty, Kevin J.; Siddoway, Michael

2010-07-01

Gas-solid fluidized beds are common in chemical processing and energy production industries. These types of reactors frequently have banks of tubes immersed within the bed to provide heating or cooling, and it is important that the fluid dynamics within these bundles is efficient and uniform. This paper presents a simple, low-cost method for quantitatively analyzing the behavior of gas bubbles within banks of tubes in a fluidized bed cold flow model. Two probes, one containing an infrared emitter and one containing an infrared (IR) detector, are placed into adjacent glass tubes such that the emitter and detector face each other. As bubbles pass through the IR beam, the detector signal increases due to less solid material blocking the path between the emitter and detector. By calibrating the signal response to known voidage of the material, one can measure the bubble voidage at various locations within the tube bundle. The rate and size of bubbles passing through the beam can also be determined by high frequency data collection and subsequent analysis. This technique allows one to develop a map of bubble voidage within a fluidized bed, which can be useful for model validation and system optimization.

Numerical simulation and experimental validation of the dynamics of multiple bubble merger during pool boiling under microgravity conditions.

PubMed

Abarajith, H S; Dhir, V K; Warrier, G; Son, G

2004-11-01

Numerical simulation and experimental validation of the growth and departure of multiple merging bubbles and associated heat transfer on a horizontal heated surface during pool boiling under variable gravity conditions have been performed. A finite difference scheme is used to solve the equations governing mass, momentum, and energy in the vapor liquid phases. The vapor-liquid interface is captured by a level set method that is modified to include the influence of phase change at the liquid-vapor interface. Water is used as test liquid. The effects of reduced gravity condition and orientation of the bubbles on the bubble diameter, interfacial structure, bubble merger time, and departure time, as well as local heat fluxes, are studied. In the experiments, multiple vapor bubbles are produced on artificial cavities in the 2-10 micrometer diameter range, microfabricated on the polished silicon wafer with given spacing. The wafer was heated electrically from the back with miniature strain gage type heating elements in order to control the nucleation superheat. The experiments conducted in normal Earth gravity and in the low gravity environment of KC-135 aircraft are used to validate the numerical simulations.

Cavitation in confined water: ultra-fast bubble dynamics

NASA Astrophysics Data System (ADS)

Vincent, Olivier; Marmottant, Philippe

2012-02-01

In the hydraulic vessels of trees, water can be found at negative pressure. This metastable state, corresponding to mechanical tension, is achieved by evaporation through a porous medium. It can be relaxed by cavitation, i.e. the sudden nucleation of vapor bubbles. Harmful for the tree due to the subsequent emboli of sap vessels, cavitation is on the contrary used by ferns to eject spores very swiftly. We will focus here on the dynamics of the cavitation bubble, which is of primary importance to explain the previously cited natural phenomena. We use the recently developed method of artificial tress, using transparent hydrogels as the porous medium. Our experiments, on water confined in micrometric hydrogel cavities, show an extremely fast dynamics: bubbles are nucleated at the microsecond timescale. For cavities larger than 100 microns, the bubble ``rings'' with damped oscillations at MHz frequencies, whereas for smaller cavities the oscillations become overdamped. This rich dynamics can be accounted for by a model we developed, leading to a modified Rayleigh-Plesset equation. Interestingly, this model predicts the impossibility to nucleate bubbles above a critical confinement that depends on liquid negative pressure and corresponds to approximately 100 nm for 20 MPa tensions.

A system for measuring bubble voidage and frequency around tubes immersed in a fluidized bed of particles.

PubMed

Whitty, Kevin J; Siddoway, Michael

2010-07-01

Gas-solid fluidized beds are common in chemical processing and energy production industries. These types of reactors frequently have banks of tubes immersed within the bed to provide heating or cooling, and it is important that the fluid dynamics within these bundles is efficient and uniform. This paper presents a simple, low-cost method for quantitatively analyzing the behavior of gas bubbles within banks of tubes in a fluidized bed cold flow model. Two probes, one containing an infrared emitter and one containing an infrared (IR) detector, are placed into adjacent glass tubes such that the emitter and detector face each other. As bubbles pass through the IR beam, the detector signal increases due to less solid material blocking the path between the emitter and detector. By calibrating the signal response to known voidage of the material, one can measure the bubble voidage at various locations within the tube bundle. The rate and size of bubbles passing through the beam can also be determined by high frequency data collection and subsequent analysis. This technique allows one to develop a map of bubble voidage within a fluidized bed, which can be useful for model validation and system optimization.

Captivity induces hyper-inflammation in the house sparrow (Passer domesticus).

PubMed

Martin, Lynn B; Kidd, Laura; Liebl, Andrea L; Coon, Courtney A C

2011-08-01

Some species thrive in captivity but others exhibit extensive psychological and physiological deficits, which can be a challenge to animal husbandry and conservation as well as wild immunology. Here, we investigated whether captivity duration impacted the regulation of a key innate immune response, inflammation, of a common wild bird species, the house sparrow (Passer domesticus). Inflammation is one of the most commonly induced and fast-acting immune responses animals mount upon exposure to a parasite. However, attenuation and resolution of inflammatory responses are partly coordinated by glucocorticoid hormones, hormones that can be disregulated in captivity. Here, we tested whether captivity duration alters corticosterone regulation and hence the inflammatory response by comparing the following responses to lipopolysaccharide (LPS; a Gram-negative bacteria component that induces inflammation) of birds caught wild and injected immediately versus those held for 2 or 4 weeks in standard conditions: (1) the magnitude of leukocyte immune gene expression [the cytokines, interleukin 1β and interleukin 6, and Toll-like receptor 4 (TLR4)], (2) the rate of clearance of endotoxin, and (3) the release of corticosterone (CORT) in response to endotoxin (LPS). We predicted that captivity duration would increase baseline CORT and thus suppress gene expression and endotoxin clearance rate. However, our predictions were not supported: TLR4 expression increased with time in captivity irrespective of LPS, and cytokine expression to LPS was stronger the longer birds remained captive. Baseline CORT was not affected by captivity duration, but CORT release post-LPS occurred only in wild birds. Lastly, sparrows held captive for 4 weeks maintained significantly higher levels of circulating endotoxin than other groups, perhaps due to leakage of microbes from the gut, but exogenous LPS did not increase circulating levels over the time scale samples were collected. Altogether, captivity appears to have induced a hyper-inflammatory state in house sparrows, perhaps due to disregulation of glucocorticoids, natural microflora or both.

The Release of a Captive-Raised Female African Elephant (Loxodonta africana) in the Okavango Delta, Botswana

PubMed Central

Evans, Kate; Moore, Randall J.; Harris, Stephen

2013-01-01

Simple Summary Managing captive elephants poses a significant challenge because of their complex social behaviour. While wild female elephants live in close-knit family groups of related individuals, captive herds often consist of unrelated animals. Some of the elephants in captive groups may be excluded by their companions and experience increased aggression, so that their welfare is compromised. There is no easy solution to this problem and novel approaches are required since slaughter of captive elephants is not publicly acceptable. We show that captive-raised female elephants can be released into the wild, survive and reproduce, and suggest that this management option should be explored further for female elephants currently held under various captive conditions. Abstract Wild female elephants live in close-knit matrilineal groups and housing captive elephants in artificial social groupings can cause significant welfare issues for individuals not accepted by other group members. We document the release of a captive-raised female elephant used in the safari industry because of welfare and management problems. She was fitted with a satellite collar, and spatial and behavioural data were collected over a 17-month period to quantify her interactions with the wild population. She was then monitored infrequently for a further five-and-a-half years. We observed few signs of aggression towards her from the wild elephants with which she socialized. She used an area of comparable size to wild female elephants, and this continued to increase as she explored new areas. Although she did not fully integrate into a wild herd, she had three calves of her own, and formed a social unit with another female and her calf that were later released from the same captive herd. We recommend that release to the wild be considered as a management option for other captive female elephants. PMID:26487408

Serum chemistry comparisons between captive and free-ranging giraffes (Giraffa camelopardalis).

PubMed

Schmidt, Debra A; Barbiers, Robyn B; Ellersieck, Mark R; Ball, Ray L; Koutsos, Elizabeth A; Griffin, Mark E; Grobler, Douw; Citino, Scott B; Bush, Mitchell

2011-03-01

Serum chemistry analyses were compared between captive and free-ranging giraffes (Giraffa camelopardalis) in an attempt to better understand some of the medical issues seen with captive giraffes. Illnesses, including peracute mortality, energy malnutrition, pancreatic disease, urolithiasis, hoof disease, and severe intestinal parasitism, may be related to zoo nutrition and management issues. Serum samples were collected from 20 captive giraffes at 10 United States institutions. Thirteen of the captive animal samples were collected from animals trained for blood collection; seven were banked samples obtained from a previous serum collection. These samples were compared with serum samples collected from 24 free-ranging giraffes in South Africa. Differences between captive and free-ranging giraffes, males and females, and adults and subadults were analyzed by using a 2 x 2 x 2 factorial and Fisher's least significant difference for mean separation; when necessary variables were ranked and analyzed via analysis of variance. Potassium and bilirubin concentrations and alanine aminotransferase (ALT) activities were different between captive and free-ranging giraffes, but all fell within normal bovid reference ranges. The average glucose concentration was significantly elevated in free-ranging giraffes (161 mg/dl) compared with captive giraffes (113 mg/dl). All giraffes in this study had glucose concentrations higher than bovine (42-75 mg/ dl) and caprine (48-76 mg/dl) reference ranges. Differences were also seen in lipase, chloride, and magnesium though these findings are likely not clinically significant. There were no differences detected between sexes. Adults had higher concentrations of potassium, total protein, globulins, and chloride and higher gamma glutamyltransferase activities, whereas subadults had higher concentrations of phosphorus. Within the captive group, nonimmobilized animals had higher concentrations of total protein and globulins. Captive giraffe diets need further investigation to determine if the differences seen in this study, especially glucose and bilirubin concentrations and ALT activities, may result in some health problems often seen in captive giraffes.

The Three-Dimensional Morphological Effects of Captivity

PubMed Central

Hartstone-Rose, Adam; Selvey, Hannah; Villari, Joseph R.; Atwell, Madeline; Schmidt, Tammy

2014-01-01

Many captive animals are fed diets that are drastically different in mechanical properties than their wild diet. Most captive pantherines are fed a nutritionally supplemented diet consisting almost entirely of ground meat. While many zoos supplement this diet with bones, the fact remains that large captive felids are fed diets that require substantially less masticatory effort than those of their wild counterparts. The osteological effects of this dietary difference have not been fully evaluated. To this end, we compared linear measurements and 3D geometric morphometric landmarks of captive and wild lions and tigers. Using Principal Component (PC) analysis of the linear measurements, not only were the sexes and species statistically distinct, but so too was the population clearly divisible in terms of captivity status. The 3D analysis supported these findings: although the most influential variable in the sample (PC1, 21.5% of the variation) separates the two species, the second most influential contributor (PC2) to the overall skull shape is driven not by the sex differences in these highly dimorphic species, but rather by their captivity status. In fact, captivity status drives nearly twice as much of the 3D variation as sexual dimorphism (14.8% vs. 8.0% for PC2 vs. PC3). Thus the shape is influenced nearly twice as much by whether the animal was captive or wild than by whether it was male or female. If a causal relationship can be demonstrated between dietary mechanical properties and morphology, people who oversee the diets of captive carnivores should consider modifying these diets to account for not only nutritional but also the mechanical properties of a carcass-based diet as well. In addition to the husbandry implications, our analyses show the ways in which captive specimens are different than their wild counterparts – findings that have implications for morphologists when considering anatomical samples. PMID:25409498

Bubble technique for Descemet membrane endothelial keratoplasty tissue preparation in an eye bank: air or liquid?

PubMed

Ruzza, Alessandro; Parekh, Mohit; Salvalaio, Gianni; Ferrari, Stefano; Camposampiero, Davide; Amoureux, Marie-Claude; Busin, Massimo; Ponzin, Diego

2015-03-01

To compare the big-bubble method using air and liquid as medium of separation for Descemet membrane endothelial keratoplasty (DMEK) lenticule preparation in an eye bank. Donor corneas (n=20) were immersed in liquid [tissue culture medium (TCM)]. Air and liquid was injected using a 25-gauge needle in the posterior stroma or as near to the stroma-Descemet membrane (DM) phase as possible to create a complete bubble of larger diameter. The endothelial cell density and mortality were checked pre- and postbubble after deflating the tissue. Four pairs of tissues were used to analyse the intracellular tight junctions and three pairs for histological examination and DNA integrity studies, respectively. The yield obtained using air was 80%, whereas that with liquid was 100%. Single injection was required in six cases; twice in two cases; three and four times in one case each with air bubble, whereas seven cases required single injection; twice in two cases; and thrice in just one case with liquid bubble. The average diameter of the final lenticule was 9.12 (±1.71) mm for air bubble and 9.78 (±1.75) mm for liquid bubble with p=0.4362 (no statistical significance). Endothelial cell mortality postbubble preparation was 8.9 (±12.38)% for air and 6.25 (±9.57)% for liquid (p=0.6268). DM and endothelium could be separated exclusively using air or liquid bubble. However, liquid bubble seems to have certain advantages over air such as the generation of yield, larger diameter and higher maintenance of endothelial cell density and integrity. © 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

The Effect on Colon Visualization During Colonoscopy of the Addition of Simethicone to Polyethylene Glycol-Electrolyte Solution: A Randomized Single-Blind Study

PubMed Central

Matro, Rebecca; Tupchong, Keegan; Daskalakis, Constantine; Gordon, Victoria; Katz, Leo; Kastenberg, David

2012-01-01

OBJECTIVES: Colonic bubbles associated with polyethylene glycol-electrolyte solution (PEG-ELS) are common and obscure mucosal visualization. This study aimed to determine whether adding simethicone decreases the incidence of bubbles. METHODS: Prospective, single-blind, randomized comparison of split dose PEG-ELS vs. PEG-ELS+simethicone (PEG-S) for outpatient colonoscopy. Bubble severity for colonic segments was assessed on withdrawal as A=no/minimal bubbles, B=moderate bubbles/interfere with detecting 5 mm polyp, C=severe bubbles/interfere with detecting 10 mm polyp. Primary end point was Grade B or C bubbles in any colon segment. Secondary end points were cleansing quality, incidence and severity of side effects, and polyp detection. RESULTS: One hundred and thirty nine patients enrolled; 13 withdrew before colonoscopy. Of 123 patients evaluated, 62 took PEG-S and 61 PEG-ELS. The incidence of grade B or C bubbles was much lower with PEG-S compared with PEG-ELS (2% vs. 38% P=0.001). Overall cleansing (excellent or good) quality was not significantly different for either the whole colon (89% PEG-ELS, 94% of PEG-S, P=0.529) or right colon (88% PEG-ELS, 94% PEG-S, P=0.365). More PEG-S patients had excellent rather than good preps (whole colon 53% vs. 28%, P=0.004; right colon 53% vs. 35%, P=0.044). Need for any flushing was less with PEG-S (38% vs. 70%, P=0.001). The groups were not significantly different with respect to total procedure and withdrawal times, incidence or severity of side effects, or number of polyps/patient or adenomas/patient. CONCLUSIONS: Adding simethicone to PEG-ELS effectively eliminates bubbles, substantially reduces the need for flushing, and results in more excellent preparations. PMID:23238113

Testing of microsatellite multiplexes for individual identification of Cape Parrots (Poicephalus robustus): paternity testing and monitoring trade

PubMed Central

Coetzer, Willem G.; Downs, Colleen T.; Perrin, Mike R.

2017-01-01

Background Illegal trade in rare wildlife species is a major threat to many parrot species around the world. Wildlife forensics plays an important role in the preservation of endangered or threatened wildlife species. Identification of illegally harvested or traded animals through DNA techniques is one of the many methods used during forensic investigations. Natural populations of the South African endemic Cape Parrot (Poicephalus robustus) are negatively affected by the removal of eggs and chicks for the pet trade. Methods In this study, 16 microsatellite markers specifically designed for the South African endemic Cape Parrot (P. robustus) are assessed for their utility in forensic casework. Using these 16 loci, the genetic diversity of a subset of the captive Cape Parrot population was also assessed and compared to three wild Cape Parrot populations. Results It was determined that the full 16 locus panel has sufficient discriminatory power to be used in parentage analyses and can be used to determine if a bird has been bred in captivity and so can be legally traded or if it has been illegally removed from the wild. In cases where birds have been removed from the wild, this study suggests that a reduced 12 locus microsatellite panel has sufficient power to assign confiscated birds to geographic population of origin. Discussion The level of genetic diversity observed within the captive Cape Parrot population was similar to that observed in the wild populations, which suggests that the captive population is not suffering from decreased levels of genetic diversity. The captive Cape Parrots did however have double the number of private alleles compared to that observed in the most genetically diverse wild population. This is probably due to the presence of rare alleles present in the founder population, which has not been lost due to genetic drift, as many of the individuals tested in this study are F1–F3 wild descendants. The results from this study provide a suit of markers that can be used to aid conservation and law enforcement authorities to better control legal and illegal trade of this South African endemic. PMID:28344897

Generation of nanobubbles by ceramic membrane filters: The dependence of bubble size and zeta potential on surface coating, pore size and injected gas pressure.

PubMed

Ahmed, Ahmed Khaled Abdella; Sun, Cuizhen; Hua, Likun; Zhang, Zhibin; Zhang, Yanhao; Zhang, Wen; Marhaba, Taha

2018-07-01

Generation of gaseous nanobubbles (NBs) by simple, efficient, and scalable methods is critical for industrialization and applications of nanobubbles. Traditional generation methods mainly rely on hydrodynamic, acoustic, particle, and optical cavitation. These generation processes render issues such as high energy consumption, non-flexibility, and complexity. This research investigated the use of tubular ceramic nanofiltration membranes to generate NBs in water with air, nitrogen and oxygen gases. This system injects pressurized gases through a tubular ceramic membrane with nanopores to create NBs. The effects of membrane pores size, surface energy, and the injected gas pressures on the bubble size and zeta potential were examined. The results show that the gas injection pressure had considerable effects on the bubble size, zeta potential, pH, and dissolved oxygen of the produced NBs. For example, increasing the injection air pressure from 69 kPa to 414 kPa, the air bubble size was reduced from 600 to 340 nm respectively. Membrane pores size and surface energy also had significant effects on sizes and zeta potentials of NBs. The results presented here aim to fill out the gaps of fundamental knowledge about NBs and development of efficient generation methods. Copyright © 2018 Elsevier Ltd. All rights reserved.

The calculation of weakly non-spherical cavitation bubble impact on a solid

NASA Astrophysics Data System (ADS)

Aganin, A. A.; Guseva, T. S.; Kosolapova, L. A.; Khismatullina, N. A.

2016-11-01

The effect of small spheroidal non-sphericity of a cavitation bubble touching a solid at the beginning of its collapse on its impact on the solid of a copper-nickel alloy is investigated. The impact on the solid is realized by means of a high-speed liquid jet arising at collapse on the bubble surface. The shape of the jet, its velocity and pressure are calculated by the boundary element method. The spatial and temporal characteristics of the pressure pulses on the solid surface are determined by the CIP-CUP method on dynamically adaptive grids without explicitly separating the gas-liquid interface. The solid surface layer dynamics is evaluated by the Godunov method. The results are analyzed in dimensionless variables obtained with using the water hammer pressure, the time moment and the jet-solid contact area radius at which the jet begins to spread on the solid surface. It is shown that in those dimensionless variables, the dependence of the spatial and temporal characteristics of the solid surface pressure pulses on the initial bubble shape non-sphericity is relatively small. The nonsphericity also slightly influences the main qualitative features of the dynamic processes inside the solid, whereas its effect on their quantitative characteristics can be significant.

Constraining pre-eruptive volatile contents and degassing histories in submarine lavas

NASA Astrophysics Data System (ADS)

Jones, M.; Soule, S. A.; Liao, Y.; Le Roux, V.; Brodsky, H.; Kurz, M. D.

2017-12-01

Vesicle textures in submarine lavas have been used to calculate total (pre-eruption) volatile concentrations in mid-ocean ridge basalts (MORB), which provide constraints on upper mantle volatile contents and CO2 fluxes along the global MOR. In this study, we evaluate vesicle size distributions and volatile contents in a suite of 20 MORB samples, which span the range of typical vesicularities and bubble number densities observed in global MORB. We demonstrate that 2D imaging coupled with traditional stereological methods closely reproduces vesicle size distributions and vesicularities measured using 3D x-ray micro-computed tomography (μ-CT). We further demonstrate that x-ray μ-CT provides additional information about bubble deformation and clustering that are linked to bubble nucleation and lava emplacement dynamics. The validation of vesicularity measurements allows us to evaluate the methods for calculating total CO2 concentrations in MORB using dissolved volatile content (SIMS), vesicularity, vesicle gas density, and equations of state. We model bubble and melt contraction during lava quenching and show that the melt viscosity prevents bubbles from reaching equilibrium at the glass transition temperature. Thus, we suggest that higher temperatures should be used to calculate exsolved volatile concentrations based on observed vesicularities. Our revised method reconciles discrepancies between exsolved volatile contents measured by gas manometry and calculated from vesicularity. In addition, our revised method suggests that some previous studies may have overestimated MORB volatile concentrations by up to a factor of two, with the greatest differences in samples with the highest vesicularities (e.g., `popping rock' 2πD43). These new results have important implications for CO2/Nb of `undegassed' MORB and global ridge CO2 fluxes. Lastly, our revised method yields constant total CO2 concentrations in sample suites from individual MOR eruptions that experienced syn-eruptive degassing. These results imply closed-system degassing during magma ascent and emplacement following equilibration at the depth of melt storage in the crust.

Diversity and distribution of avian malaria and related haemosporidian parasites in captive birds from a Brazilian megalopolis.

PubMed

Chagas, Carolina Romeiro Fernandes; Valkiūnas, Gediminas; de Oliveira Guimarães, Lilian; Monteiro, Eliana Ferreira; Guida, Fernanda Junqueira Vaz; Simões, Roseli França; Rodrigues, Priscila Thihara; de Albuquerque Luna, Expedito José; Kirchgatter, Karin

2017-02-17

The role of zoos in conservation programmes has increased significantly in last decades, and the health of captive animals is essential to guarantee success of such programmes. However, zoo birds suffer from parasitic infections, which often are caused by malaria parasites and related haemosporidians. Studies determining the occurrence and diversity of these parasites, aiming better understanding infection influence on fitness of captive birds, are limited. In 2011-2015, the prevalence and diversity of Plasmodium spp. and Haemoproteus spp. was examined in blood samples of 677 captive birds from the São Paulo Zoo, the largest zoo in Latin America. Molecular and microscopic diagnostic methods were used in parallel to detect and identify these infections. The overall prevalence of haemosporidians was 12.6%. Parasites were mostly detected by the molecular diagnosis, indicating that many birds harbour subclinical or abortive infections. In this project, birds of 17 orders (almost half of all the orders currently accepted in taxonomy of birds), 29 families, and 122 species, were tested, detecting positive individuals in 27% of bird species. Birds from the Anatidae were the most prevalently infected (64.7% of all infected animals). In all, infections with parasites of the genus Plasmodium (overall prevalence 97.6%) predominated when compared to those of the genus Haemoproteus (2.4%). In total, 14 cytochrome b (cytb) lineages of Plasmodium spp. and 2 cytb lineages of Haemoproteus spp. were recorded. Eight lineages were new. One of the reported lineages was broad generalist while others were reported in single or a few species of birds. Molecular characterization of Haemoproteus ortalidum was developed. This study shows that many species of birds are at risk in captivity. It is difficult to stop haemosporidian parasite transmission in zoos, but is possible to reduce the infection rate by treating the infected animals or/and while keeping them in facilities free from mosquitoes. Protocols of quarantine should be implemented whenever an animal is transferred between bird maintaining institutions. This is the first survey of haemosporidians in captive birds from different orders maintained in zoos. It is worth emphasizing the necessity of applying practices to control these parasites in management and husbandry of animals in captivity.

Finite-sized gas bubble motion in a blood vessel: Non-Newtonian effects

PubMed Central

Mukundakrishnan, Karthik; Ayyaswamy, Portonovo S.; Eckmann, David M.

2009-01-01

We have numerically investigated the axisymmetric motion of a finite-sized nearly occluding air bubble through a shear-thinning Casson fluid flowing in blood vessels of circular cross section. The numerical solution entails solving a two-layer fluid model—a cell-free layer and a non-Newtonian core together with the gas bubble. This problem is of interest to the field of rheology and for gas embolism studies in health sciences. The numerical method is based on a modified front-tracking method. The viscosity expression in the Casson model for blood (bulk fluid) includes the hematocrit [the volume fraction of red blood cells (RBCs)] as an explicit parameter. Three different flow Reynolds numbers, Reapp=ρlUmaxd/μapp, in the neighborhood of 0.2, 2, and 200 are investigated. Here, ρl is the density of blood, Umax is the centerline velocity of the inlet Casson profile, d is the diameter of the vessel, and μapp is the apparent viscosity of whole blood. Three different hematocrits have also been considered: 0.45, 0.4, and 0.335. The vessel sizes considered correspond to small arteries, and small and large arterioles in normal humans. The degree of bubble occlusion is characterized by the ratio of bubble to vessel radius (aspect ratio), λ, in the range 0.9≤λ≤1.05. For arteriolar flow, where relevant, the Fahraeus-Lindqvist effects are taken into account. Both horizontal and vertical vessel geometries have been investigated. Many significant insights are revealed by our study: (i) bubble motion causes large temporal and spatial gradients of shear stress at the “endothelial cell” (EC) surface lining the blood vessel wall as the bubble approaches the cell, moves over it, and passes it by; (ii) rapid reversals occur in the sign of the shear stress (+ → − → +) imparted to the cell surface during bubble motion; (iii) large shear stress gradients together with sign reversals are ascribable to the development of a recirculation vortex at the rear of the bubble; (iv) computed magnitudes of shear stress gradients coupled with their sign reversals may correspond to levels that cause injury to the cell by membrane disruption through impulsive compression and stretching; and (v) for the vessel sizes and flow rates investigated, gravitational effects are negligible. PMID:18851139

Degassing of H2O in a phonolitic melt: A closer look at decompression experiments

NASA Astrophysics Data System (ADS)

Marxer, Holger; Bellucci, Philipp; Nowak, Marcus

2015-05-01

Melt degassing during magma ascent is controlled by the decompression rate and can be simulated in decompression experiments. H2O-bearing phonolitic melts were decompressed at a super-liquidus T of 1323 K in an internally heated argon pressure vessel, applying continuous decompression (CD) as well as to date commonly used step-wise decompression (SD) techniques to investigate the effect of decompression method on melt degassing. The hydrous melts were decompressed from 200 MPa at nominal decompression rates of 0.0028-1.7 MPa·s- 1. At final pressure (Pfinal), the samples were quenched rapidly at isobaric conditions with ~ 150 K·s- 1. The bubbles in the quenched samples are often deformed and dented. Flow textures in the glass indicate melt transport at high viscosity. We suggest that this observation is due to bubble shrinkage during quench. This general problem was mostly overlooked in the interpretation of experimentally degassed samples to date. Bubble shrinkage due to decreasing molar volume (Vm) of the exsolved H2O in the bubbles occurs during isobaric rapid quench until the melt is too viscous too relax. The decrease of Vm(H2O) during cooling at Pfinal of the experiments results in a decrease of the bubble volume by a shrinking factor Bs: At nominal decompression rates > 0.17 MPa·s- 1 and a Pfinal of 75 MPa, the decompression method has only minor influence on melt degassing. SD and CD result in high bubble number densities of 104-105 mm- 3. Fast P drop leads to immediate supersaturation with H2O in the melt. At such high nominal decompression rates, the diffusional transport of H2O is limited and therefore bubble nucleation is the predominant degassing process. The residual H2O contents in the melts decompressed to 75 MPa increase with nominal decompression rate. After homogeneous nucleation is triggered, CD rates ≤ 0.024 MPa·s- 1 facilitate continuous reduction of the supersaturation by H2O diffusion into previously nucleated bubbles. Bubble number densities of CD samples with low nominal decompression rates are several orders of magnitude lower than for SD experiments and the bubble diameters are larger. The reproducibility of MSD experiments with low nominal decompression rates is worse than for CD runs. Commonly used SD techniques are therefore not suitable to simulate melt degassing during continuous magma ascent with low ascent rates.

Extrinsic factors significantly affect patterns of disease in free-ranging and captive cheetah (Acinonyx jubatus) populations.

PubMed

Munson, Linda; Terio, Karen A; Worley, Michael; Jago, Mark; Bagot-Smith, Arthur; Marker, Laurie

2005-07-01

The cheetah (Acinonyx jubatus) has been considered a paradigm for disease vulnerability due to loss of genetic diversity. This species monomorphism has been suspected to be the basis for their general poor health and dwindling populations in captivity. North American and South African captive populations have high prevalences of hepatic veno-occlusive disease, glomerulosclerosis, gastritis, and systemic amyloidosis, diseases that are rare in other species. Unusually severe inflammatory reactions to common infectious agents have also been documented in captive cheetahs. The current study compared disease prevalences in free-ranging Namibian cheetahs with those in two captive populations of similar ages. The occurrence of diseases in the free-ranging population was determined from 49 necropsies and 27 gastric biopsies obtained between 1986 and 2003 and compared with prevalences in 147 North American and 80 South African captive cheetahs. Except for two cheetahs, the free-ranging population was in robust health with only mild lesions present, in contrast with significantly higher prevalences in the captive populations. Despite widespread heavy Helicobacter colonization in wild cheetahs, only 3% of the free-ranging population had moderate to severe gastritis, in contrast with 64% of captive cheetahs. No severe inflammatory reactions to viral infections were detected in the free-ranging animals. Because free-ranging Namibian cheetahs are as genetically impoverished as captive cheetahs, these findings caution against attributing loss of fitness solely to genetic factors and attest to the fundamental importance of extrinsic factors in wildlife health.

Hyperlipidemia and reproductive failure in captive-reared alligators: vitamin E, vitamin A, plasma lipids, fatty acids, and steroid hormones.

PubMed

Lance, V A; Morici, L A; Elsey, R M; Lund, E D; Place, A R

2001-02-01

Blood samples were collected from 26 captive-reared alligators (25 females; one male) and 12 (seven females and five males) wild "nuisance" alligators collected by wildlife personnel in south Louisiana in May 1995. The captive alligators, hatched from artificially incubated eggs in 1972-1973, had received vitamin E supplements during the 3 weeks before the blood sample was collected. Each sample was analyzed for vitamin E (alpha-tocopherol), vitamin A (retinol), total lipid, triacylglycerol, phospholipid, cholesterol, cholesteryl ester, free fatty acids, steroid hormones and a standard clinical blood panel. The fatty acid composition of the plasma lipid fraction was also analyzed. Results indicated that 18 of the captive females and three of the seven wild females were undergoing vitellogenesis, i.e. had elevated plasma estradiol and elevated plasma calcium. Vitellogenic females had higher vitamin E than non-vitellogenic females (77.4 microg/ml vs. 28.6 microg/ml in captive females; 24.0 microg/ml vs. 21 microg/ml in wild females). Plasma retinol was similar in all groups, ranging from 0.5 to 1.4 microg/ml and close to values reported in birds. All lipid fractions, with the exception of cholesteryl ester, were higher in captive alligators than in wild alligators. There were also significant differences in the fatty acid composition of wild and captive alligators. Plasma eicosapentaenoic and docasahexaenoic acid were higher in wild than in captive alligators, whereas linoleic was higher in captive than in wild.

Modeling of sonochemistry in water in the presence of dissolved carbon dioxide.

PubMed

Authier, Olivier; Ouhabaz, Hind; Bedogni, Stefano

2018-07-01

CO 2 capture and utilization (CCU) is a process that captures CO 2 emissions from sources such as fossil fuel power plants and reuses them so that they will not enter the atmosphere. Among the various ways of recycling CO 2 , reduction reactions are extensively studied at lab-scale. However, CO 2 reduction by standard methods is difficult. Sonochemistry may be used in CO 2 gas mixtures bubbled through water subjected to ultrasound waves. Indeed, the sonochemical reduction of CO 2 in water has been already investigated by some authors, showing that fuel species (CO and H 2 ) are obtained in the final products. The aim of this work is to model, for a single bubble, the close coupling of the mechanisms of bubble dynamics with the kinetics of gas phase reactions in the bubble that can lead to CO 2 reduction. An estimation of time-scales is used to define the controlling steps and consequently to solve a reduced model. The calculation of the concentration of free radicals and gases formed in the bubble is undertaken over many cycles to look at the effects of ultrasound frequency, pressure amplitude, initial bubble radius and bubble composition in CO 2 . The strong effect of bubble composition on the CO 2 reduction rate is confirmed in accordance with experimental data from the literature. When the initial fraction of CO 2 in the bubble is low, bubble growth and collapse are slightly modified with respect to simulation without CO 2 , and chemical reactions leading to CO 2 reduction are promoted. However, the peak collapse temperature depends on the thermal properties of the CO 2 and greatly decreases as the CO 2 increases in the bubble. The model shows that initial bubble radius, ultrasound frequency and pressure amplitude play a critical role in CO 2 reduction. Hence, in the case of a bubble with an initial radius of around 5 μm, CO 2 reduction appears to be more favorable at a frequency around 300 kHz than at a low frequency of around 20 kHz. Finally, the industrial application of ultrasound to CO 2 reduction in water would be largely dependent on sonochemical efficiency. Under the conditions tested, this process does not seem to be sufficiently efficient. Copyright © 2018 Elsevier B.V. All rights reserved.

Pulsed electrical discharge in gas bubbles in water

NASA Astrophysics Data System (ADS)

Gershman, Sophia

A phenomenological picture of pulsed electrical discharge in gas bubbles in water is produced by combining electrical, spectroscopic, and imaging methods. The discharge is generated by applying one microsecond long 5 to 20 kilovolt pulses between the needle and disk electrodes submerged in water. A gas bubble is generated at the tip of the needle electrode. The study includes detailed experimental investigation of the discharge in argon bubbles and a brief look at the discharge in oxygen bubbles. Imaging, electrical characteristics, and time-resolved optical emission data point to a fast streamer propagation mechanism and formation of a plasma channel in the bubble. Spectroscopic methods based on line intensity ratios and Boltzmann plots of line intensities of argon, atomic hydrogen, and argon ions and the examination of molecular emission bands from molecular nitrogen and hydroxyl radicals provide evidence of both fast beam-like electrons and slow thermalized ones with temperatures of 0.6 -- 0.8 electron-volts. The collisional nature of plasma at atmospheric pressure affects the decay rates of optical emission. Spectroscopic study of rotational-vibrational bands of hydroxyl radical and molecular nitrogen gives vibrational and rotational excitation temperatures of the discharge of about 0.9 and 0.1 electron-volt, respectively. Imaging and electrical evidence show that discharge charge is deposited on the bubble wall and water serves as a dielectric barrier for the field strength and time scales of this experiment. Comparing the electrical and imaging information for consecutive pulses applied at a frequency of 1 Hz indicates that each discharge proceeds as an entirely new process with no memory of the previous discharge aside from long-lived chemical species, such as ozone and oxygen. Intermediate values for the discharge gap and pulse duration, low repetition rate, and unidirectional character of the applied voltage pulses make the discharge process here unique compared to the traditional corona or dielectric barrier discharges. These conditions make the experimental evidence presented in this work valuable for the advancement of modeling and the theoretical understanding of the discharge in bubbles in water.

Visualization of the hot chocolate sound effect by spectrograms

NASA Astrophysics Data System (ADS)

Trávníček, Z.; Fedorchenko, A. I.; Pavelka, M.; Hrubý, J.

2012-12-01

We present an experimental and a theoretical analysis of the hot chocolate effect. The sound effect is evaluated using time-frequency signal processing, resulting in a quantitative visualization by spectrograms. This method allows us to capture the whole phenomenon, namely to quantify the dynamics of the rising pitch. A general form of the time dependence volume fraction of the bubbles is proposed. We show that the effect occurs due to the nonlinear dependence of the speed of sound in the gas/liquid mixture on the volume fraction of the bubbles and the nonlinear time dependence of the volume fraction of the bubbles.

Long-lived oscillons from asymmetric bubbles: Existence and stability

NASA Astrophysics Data System (ADS)

Adib, Artur B.; Gleiser, Marcelo; Almeida, Carlos A.

2002-10-01

The possibility that extremely long-lived, time-dependent, and localized field configurations (``oscillons'') arise during the collapse of asymmetrical bubbles in (2+1)-dimensional φ4 models is investigated. It is found that oscillons can develop from a large spectrum of elliptically deformed bubbles. Moreover, we provide numerical evidence that such oscillons are (a) circularly symmetric and (b) linearly stable against small arbitrary radial and angular perturbations. The latter is based on a dynamical approach designed to investigate the stability of nonintegrable time-dependent configurations that is capable of probing slowly growing instabilities not seen through the usual ``spectral'' method.

Surface tension effects on the behavior of a cavity growing, collapsing, and rebounding near a rigid wall.

PubMed

Zhang, Zhen-yu; Zhang, Hui-sheng

2004-11-01

Surface tension effects on the behavior of a pure vapor cavity or a cavity containing some noncondensible contents, which is growing, collapsing, and rebounding axisymmetrically near a rigid wall, are investigated numerically by the boundary integral method for different values of dimensionless stand-off parameter gamma, buoyancy parameter delta, and surface tension parameter beta. It is found that at the late stage of the collapse, if the resultant action of the Bjerknes force and the buoyancy force is not small, surface tension will not have significant effects on bubble behavior except that the bubble collapse time is shortened and the liquid jet becomes wider. If the resultant action of the two force is small enough, surface tension will have significant and in some cases substantial effects on bubble behavior, such as changing the direction of the liquid jet, making a new liquid jet appear, in some cases preventing the bubble from rebound before jet impact, and in other cases causing the bubble to rebound or even recollapse before jet impact. The mechanism of surface tension effects on the collapsing behavior of a cavity has been analyzed. The mechanisms of some complicated phenomena induced by surface tension effects are illustrated by analysis of the computed velocity fields and pressure contours of the liquid flow outside the bubble at different stages of the bubble evolution.

Transparent electrodes fabricated via the self-assembly of silver nanowires using a bubble template.

PubMed

Tokuno, Takehiro; Nogi, Masaya; Jiu, Jinting; Sugahara, Tohru; Suganuma, Katsuaki

2012-06-26

To shore up the demand of transparent electrodes for wide applications such as organic light emitting diodes and solar cells, transparent electrodes are required as an alternative for indium tin oxide electrodes. Herein the self-assembly method with a bubble template paves the way for cost-effective fabrication of transparent electrodes with high conductivity and transparency using self-assembly of silver nanowires (AgNWs) in a bubble template. AgNWs were first dispersed in water that was bubbled with a surfactant and a thickening agent. Furthermore, these AgNWs were assembled by lining along the bubble ridges. When the bubbles containing the AgNWs were sandwiched between two glass substrates, the bubble ridges including the AgNWs formed continuous polygonal structures. Mesh structures were formed on both glass substrates after air-drying. The mesh structures evolved into mesh transparent electrodes following heat-treatment. The AgNW mesh structure exhibited a low sheet resistance of 6.2 Ω/square with a transparency of 84% after heat treatment at 200 °C for 20 min. The performance is higher than that of transparent electrodes with random networks of AgNWs. Furthermore, the conductivity and transparency of the mesh transparent electrodes can be adjusted by changing the amount of the AgNW suspension and the space between the two glass substrates.

Shock-induced bubble collapse in a vessel: Implications for vascular injury in shockwave lithotripsy

NASA Astrophysics Data System (ADS)

Coralic, Vedran; Colonius, Tim

2014-11-01

In shockwave lithotripsy, shocks are repeatedly focused on kidney stones so to break them. The process leads to cavitation in tissue, which leads to hemorrhage. We hypothesize that shock-induced collapse (SIC) of preexisting bubbles is a potential mechanism for vascular injury. We study it numerically with an idealized problem consisting of the three-dimensional SIC of an air bubble immersed in a cylindrical water column embedded in gelatin. The gelatin is a tissue simulant and can be treated as a fluid due to fast time scales and small spatial scales of collapse. We thus model the problem as a compressible multicomponent flow and simulate it with a shock- and interface-capturing numerical method. The method is high-order, conservative and non-oscillatory. Fifth-order WENO is used for spatial reconstruction and an HLLC Riemann solver upwinds the fluxes. A third-order TVD-RK scheme evolves the solution. We evaluate the potential for injury in SIC for a range of pressures, bubble and vessel sizes, and tissue properties. We assess the potential for injury by comparing the finite strains in tissue, obtained by particle tracking, to ultimate strains from experiments. We conclude that SIC may contribute to vascular rupture and discuss the smallest bubble sizes needed for injury. This research was supported by NIH Grant No. 2PO1DK043881 and utilized XSEDE, which is supported by NSF Grant No. OCI-1053575.

Socialization of adult owl monkeys (Aotus sp.) in Captivity.

PubMed

Williams, Lawrence E; Coke, C S; Weed, J L

2017-01-01

Social housing has often been recommended as one-way to address the psychological well-being of captive non-human primates. Published reports have examined methods to socialize compatible animals by forming pairs or groups. Successful socialization rates vary depending on the species, gender, and environment. This study presents a retrospective look at pairing attempts in two species of owl monkeys, Aotus nancymaae and A. azarae, which live in monogamous pairs in the wild. The results of 477 pairing attempt conducted with captive, laboratory housed owl monkeys and 61 hr of behavioral observations are reported here. The greatest success pairing these owl monkeys occurred with opposite sex pairs, with an 82% success rate. Opposite sex pairs were more successful when females were older than males. Female-female pairs were more successful than male-male (MM) pairs (62% vs 40%). Successful pairs stayed together between 3 and 7 years before the animals were separated due to social incompatibility. Vigilance, eating, and sleeping during introductions significantly predicted success, as did the performance of the same behavior in both animals. The results of this analysis show that it is possible to give captive owl monkeys a social alternative even if species appropriate social partners (i.e., opposite sex partners) are not available. The focus of this report is a description of one potential way to enhance the welfare of a specific new world primate, the owl monkey, under laboratory conditions. More important is how the species typical social structure of owl monkeys in nature affects the captive management of this genus. Am. J. Primatol. 79:e22521, 2017. © 2015 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Adult Vampire Bats Produce Contact Calls When Isolated: Acoustic Variation by Species, Population, Colony, and Individual

PubMed Central

Carter, Gerald G.; Logsdon, Ryane; Arnold, Bryan D.; Menchaca, Angelica; Medellin, Rodrigo A.

2012-01-01

Background Bat pups produce individually distinct isolation calls to facilitate maternal recognition. Increasing evidence suggests that, in group-living bat species, adults often use similar calls to maintain contact. We investigated if isolated adults from all three species of the highly cooperative vampire bats (Phyllostomidae: Desmodontinae) would produce vocally distinct contact calls when physically isolated. Methods/Principal Findings We assessed variation in contact calls recorded from isolated captive and wild-caught adult common vampire bats (Desmodus rotundus), white-winged vampire bats (Diaemus youngi) and hairy-legged vampire bats (Diphylla ecaudata). We compared species-typical contact call structure, and used information theory and permuted discriminate function analyses to examine call structure variation, and to determine if the individuality of contact calls is encoded by different call features across species and populations. We found that isolated adult vampire bats produce contact calls that vary by species, population, colony, and individual. However, much variation occurred within a single context and individual. We estimated signature information for captive Diaemus (same colony), captive Desmodus (same colony), and wild Desmodus (different colonies) at 3.21, 3.26, and 3.88 bits, respectively. Contact calls from a captive colony of Desmodus were less individually distinct than calls from wild-caught Desmodus from different colonies. Both the degree of individuality and parameters encoding individuality differed between the bats from a single captive colony and the wild-caught individuals from different groups. This result is consistent with, but not sufficient evidence of, vocal convergence in groups. Conclusion Our results show that adult vampire bats of all three species produce highly variable contact calls when isolated. Contact calls contain sufficient information for vocal discrimination, but also possess more intra-individual variation than is required for the sole purpose of identifying individuals. PMID:22719947

Determining when to change course in management actions.

PubMed

Ng, Chooi Fei; McCarthy, Michael A; Martin, Tara G; Possingham, Hugh P

2014-12-01

Time is of the essence in conservation biology. To secure the persistence of a species, we need to understand how to balance time spent among different management actions. A new and simple method to test the efficacy of a range of conservation actions is required. Thus, we devised a general theoretical framework to help determine whether to test a new action and when to cease a trial and revert to an existing action if the new action did not perform well. The framework involves constructing a general population model under the different management actions and specifying a management objective. By maximizing the management objective, we could generate an analytical solution that identifies the optimal timing of when to change management action. We applied the analytical solution to the case of the Christmas Island pipistrelle bat (Pipistrelle murrayi), a species for which captive breeding might have prevented its extinction. For this case, we used our model to determine whether to start a captive breeding program and when to stop a captive breeding program and revert to managing the species in the wild, given that the management goal is to maximize the chance of reaching a target wild population size. For the pipistrelle bat, captive breeding was to start immediately and it was desirable to place the species in captivity for the entire management period. The optimal time to revert to managing the species in the wild was driven by several key parameters, including the management goal, management time frame, and the growth rates of the population under different management actions. Knowing when to change management actions can help conservation managers' act in a timely fashion to avoid species extinction. © 2014 Society for Conservation Biology.

Enriching the captive elephant population genetic pool through artificial insemination with frozen-thawed semen collected in the wild.

PubMed

Hildebrandt, T B; Hermes, R; Saragusty, J; Potier, R; Schwammer, H M; Balfanz, F; Vielgrader, H; Baker, B; Bartels, P; Göritz, F

2012-10-01

The first successful AI in an elephant was reported in 1998, using fresh semen. Since then almost 40 calves have been produced through AI in both Asian and African elephants worldwide. Following these successes, with the objective of enriching the captive population with genetic material from the wild, we evaluated the possibility of using frozen-thawed semen collected from wild bulls for AI in captivity. Semen, collected from a 36-yr-old wild African savanna elephant (Loxodonta africana) in South Africa was frozen using the directional freezing technique. This frozen-thawed semen was used for four inseminations over two consecutive days, two before and two after ovulation, in a 26-yr-old female African savanna elephant in Austria. Insemination dose of 1200 × 10(6) cells per AI with 61% motility resulted in pregnancy, which was confirmed through ultrasound examination 75, 110 and 141 days after the AI procedure. This represents the first successful AI using wild bull frozen-thawed semen in elephants. The incorporation of AI with frozen-thawed semen into the assisted reproduction toolbox opens the way to preserve and transport semen between distant individuals in captivity or, as was done in this study, between wild and captive populations, without the need to transport stressed or potentially disease-carrying animals or to remove animals from the wild. In addition, cryopreserved spermatozoa, in combination with AI, are useful methods to extend the reproductive lifespan of individuals beyond their biological lifespan and an important tool for genetic diversity management and phenotype selection in these endangered mammals. Copyright © 2012 Elsevier Inc. All rights reserved.

Computation of subsonic flow around airfoil systems with multiple separation

NASA Technical Reports Server (NTRS)

Jacob, K.

1982-01-01

A numerical method for computing the subsonic flow around multi-element airfoil systems was developed, allowing for flow separation at one or more elements. Besides multiple rear separation also sort bubbles on the upper surface and cove bubbles can approximately be taken into account. Also, compressibility effects for pure subsonic flow are approximately accounted for. After presentation the method is applied to several examples and improved in some details. Finally, the present limitations and desirable extensions are discussed.

Captivity, citizenship, and the ethics of otherwise in the society-of-captives thesis: a commentary on Arrigo.

PubMed

Brown, Michelle

2013-06-01

In this engagement with Professor Bruce Arrigo's psychological jurisprudence model, I explore his critique of captivity and risk management. I am particularly interested in his claims that incarceration culminates in society's own captivity, that the most destructive aspect of captivity is its foreclosing of human difference and potentiality, and that a praxis that is both clinical and mindful might point a way out. By way of a case anecdote, I interrogate several of the key terms in Arrigo's formulation-citizenship, reform, revolution, and praxis-in an effort to further conjugate from the ground up such an innovative and important set of possibilities.

Visualizing the Histotripsy Process: Bubble Cloud-Cancer Cell Interactions in a Tissue-Mimicking Environment.

PubMed

Vlaisavljevich, Eli; Maxwell, Adam; Mancia, Lauren; Johnsen, Eric; Cain, Charles; Xu, Zhen

2016-10-01

Histotripsy is a non-invasive ultrasonic ablation method that uses cavitation to mechanically fractionate tissue into acellular debris. With a sufficient number of pulses, histotripsy can completely fractionate tissue into a liquid-appearing homogenate with no cellular structures. The location, shape and size of lesion formation closely match those of the cavitation cloud. Previous work has led to the hypothesis that the rapid expansion and collapse of histotripsy bubbles fractionate tissue by inducing large stress and strain on the tissue structures immediately adjacent to the bubbles. In the work described here, the histotripsy bulk tissue fractionation process is visualized at the cellular level for the first time using a custom-built 2-MHz transducer incorporated into a microscope stage. A layer of breast cancer cells were cultured within an optically transparent fibrin-based gel phantom to mimic cells inside a 3-D extracellular matrix. To test the hypothesis, the cellular response to single and multiple histotripsy pulses was investigated using high-speed optical imaging. Bubbles were always generated in the extracellular space, and significant cell displacement/deformation was observed for cells directly adjacent to the bubble during both bubble expansion and collapse. The largest displacements were observed during collapse for cells immediately adjacent to the bubble, with cells moving more than 150-300 μm in less than 100 μs. Cells often underwent multiple large deformations (>150% strain) over multiple pulses, resulting in the bisection of cells multiple times before complete removal. To provide theoretical support to the experimental observations, a numerical simulation was conducted using a single-bubble model, which indicated that histotripsy exerts the largest strains and cell displacements in the regions immediately adjacent to the bubble. The experimental and simulation results support our hypothesis, which helps to explain the formation of the sharp lesions formed in histotripsy therapy localized to the regions directly exposed to the bubbles. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Understanding the Links among the Magnetic Fields, Filament, Bipolar Bubble, and Star Formation in RCW 57A Using NIR Polarimetry

NASA Astrophysics Data System (ADS)

Eswaraiah, Chakali; Lai, Shih-Ping; Chen, Wen-Ping; Pandey, A. K.; Tamura, M.; Maheswar, G.; Sharma, S.; Wang, Jia-Wei; Nishiyama, S.; Nakajima, Y.; Kwon, Jungmi; Purcell, R.; Magalhães, A. M.

2017-12-01

The influence of magnetic fields (B-fields) on the formation and evolution of bipolar bubbles, due to the expanding ionization fronts (I-fronts) driven by the H II regions that are formed and embedded in filamentary molecular clouds, has not been well-studied yet. In addition to the anisotropic expansion of I-fronts into a filament, B-fields are expected to introduce an additional anisotropic pressure, which might favor the expansion and propagation of I-fronts forming a bipolar bubble. We present results based on near-infrared polarimetric observations toward the central ˜8‧ × 8‧ area of the star-forming region RCW 57A, which hosts an H II region, a filament, and a bipolar bubble. Polarization measurements of 178 reddened background stars, out of the 919 detected sources in the JHK s bands, reveal B-fields that thread perpendicularly to the filament long axis. The B-fields exhibit an hourglass morphology that closely follows the structure of the bipolar bubble. The mean B-field strength, estimated using the Chandrasekhar-Fermi method (CF method), is 91 ± 8 μG. B-field pressure dominates over turbulent and thermal pressures. Thermal pressure might act in the same orientation as the B-fields to accelerate the expansion of those I-fronts. The observed morphological correspondence among the B-fields, filament, and bipolar bubble demonstrate that the B-fields are important to the cloud contraction that formed the filament, to the gravitational collapse and star formation in it, and in feedback processes. The last one includes the formation and evolution of mid-infrared bubbles by means of B-field supported propagation and expansion of I-fronts. These may shed light on preexisting conditions favoring the formation of the massive stellar cluster in RCW 57A.

Organ culture storage of pre-prepared corneal donor material for Descemet's membrane endothelial keratoplasty

PubMed Central

Bhogal, Maninder; Matter, Karl; Balda, Maria S; Allan, Bruce D

2016-01-01

Purpose To evaluate the effect of media composition and storage method on pre-prepared Descemet's membrane endothelial keratoplasty (DMEK) grafts. Methods 50 corneas were used. Endothelial wound healing and proliferation in different media were assessed using a standard injury model. DMEK grafts were stored using three methods: peeling with free scroll storage; partial peeling with storage on the stroma and fluid bubble separation with storage on the stroma. Endothelial cell (EC) phenotype and the extent of endothelial overgrowth were examined. Global cell viability was assessed for storage methods that maintained a normal cell phenotype. Results 1 mm wounds healed within 4 days. Enhanced media did not increase EC proliferation but may have increased EC migration into the wounded area. Grafts that had been trephined showed evidence of EC overgrowth, whereas preservation of a physical barrier in the bubble group prevented this. In grafts stored in enhanced media or reapposed to the stroma after trephination, endothelial migration occurred sooner and cells underwent endothelial-mesenchymal transformation. Ongoing cell loss, with new patterns of cell death, was observed after returning grafts to storage. Grafts stored as free scrolls retained more viable ECs than grafts prepared with the fluid bubble method (74.2± 3% vs 60.3±6%, p=0.04 (n=8). Conclusion Free scroll storage is superior to liquid bubble and partial peeling techniques. Free scrolls only showed overgrowth of ECs after 4 days in organ culture, indicating a viable time window for the clinical use of pre-prepared DMEK donor material using this method. Methods for tissue preparation and storage media developed for whole corneas should not be used in pre-prepared DMEK grafts without prior evaluation. PMID:27543290

40 CFR 63.11094 - What are my recordkeeping requirements?

Code of Federal Regulations, 2010 CFR

2010-07-01

...: Test pressure; pressure or vacuum change, mm of water; time period of test; number of leaks found with... § 63.11092(f)(1) and periodic railcar bubble leak testing performed under § 63.11092(f)(2). (2) The... Certification Test—Method 27 or Periodic Railcar Bubble Leak Test Procedure. (ii) Cargo tank owner's name and...

Rise of an argon bubble in liquid steel in the presence of a transverse magnetic field

NASA Astrophysics Data System (ADS)

Jin, K.; Kumar, P.; Vanka, S. P.; Thomas, B. G.

2016-09-01

The rise of gaseous bubbles in viscous liquids is a fundamental problem in fluid physics, and it is also a common phenomenon in many industrial applications such as materials processing, food processing, and fusion reactor cooling. In this work, the motion of a single argon gas bubble rising in quiescent liquid steel under an external magnetic field is studied numerically using a Volume-of-Fluid method. To mitigate spurious velocities normally generated during numerical simulation of multiphase flows with large density differences, an improved algorithm for surface tension modeling, originally proposed by Wang and Tong ["Deformation and oscillations of a single gas bubble rising in a narrow vertical tube," Int. J. Therm. Sci. 47, 221-228 (2008)] is implemented, validated and used in the present computations. The governing equations are integrated by a second-order space and time accurate numerical scheme, and implemented on multiple Graphics Processing Units with high parallel efficiency. The motion and terminal velocities of the rising bubble under different magnetic fields are compared and a reduction in rise velocity is seen in cases with the magnetic field applied. The shape deformation and the path of the bubble are discussed. An elongation of the bubble along the field direction is seen, and the physics behind these phenomena is discussed. The wake structures behind the bubble are visualized and effects of the magnetic field on the wake structures are presented. A modified drag coefficient is obtained to include the additional resistance force caused by adding a transverse magnetic field.

Rise of an argon bubble in liquid steel in the presence of a transverse magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, K.; Kumar, P.; Vanka, S. P., E-mail: spvanka@illinois.edu

2016-09-15

The rise of gaseous bubbles in viscous liquids is a fundamental problem in fluid physics, and it is also a common phenomenon in many industrial applications such as materials processing, food processing, and fusion reactor cooling. In this work, the motion of a single argon gas bubble rising in quiescent liquid steel under an external magnetic field is studied numerically using a Volume-of-Fluid method. To mitigate spurious velocities normally generated during numerical simulation of multiphase flows with large density differences, an improved algorithm for surface tension modeling, originally proposed by Wang and Tong [“Deformation and oscillations of a single gasmore » bubble rising in a narrow vertical tube,” Int. J. Therm. Sci. 47, 221–228 (2008)] is implemented, validated and used in the present computations. The governing equations are integrated by a second-order space and time accurate numerical scheme, and implemented on multiple Graphics Processing Units with high parallel efficiency. The motion and terminal velocities of the rising bubble under different magnetic fields are compared and a reduction in rise velocity is seen in cases with the magnetic field applied. The shape deformation and the path of the bubble are discussed. An elongation of the bubble along the field direction is seen, and the physics behind these phenomena is discussed. The wake structures behind the bubble are visualized and effects of the magnetic field on the wake structures are presented. A modified drag coefficient is obtained to include the additional resistance force caused by adding a transverse magnetic field.« less

Resonance Tube Phonation in Water-the Effect of Tube Diameter and Water Depth on Back Pressure and Bubble Characteristics at Different Airflows.

PubMed

Wistbacka, Greta; Andrade, Pedro Amarante; Simberg, Susanna; Hammarberg, Britta; Södersten, Maria; Švec, Jan G; Granqvist, Svante

2018-01-01

Resonance tube phonation with tube end in water is a voice therapy method in which the patient phonates through a glass tube, keeping the free end of the tube submerged in water, creating bubbles. The purpose of this experimental study was to determine flow-pressure relationship, flow thresholds between bubble types, and bubble frequency as a function of flow and back volume. A flow-driven vocal tract simulator was used for recording the back pressure produced by resonance tubes with inner diameters of 8 and 9 mm submerged at water depths of 0-7 cm. Visual inspection of bubble types through video recording was also performed. The static back pressure was largely determined by the water depth. The narrower tube provided a slightly higher back pressure for a given flow and depth. The amplitude of the pressure oscillations increased with flow and depth. Depending on flow, the bubbles were emitted from the tube in three distinct types with increasing flow: one by one, pairwise, and in a chaotic manner. The bubble frequency was slightly higher for the narrower tube. An increase in back volume led to a decrease in bubble frequency. This study provides data on the physical properties of resonance tube phonation with the tube end in water. This information will be useful in future research when looking into the possible effects of this type of voice training. Copyright © 2018 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Neutron imaging with bubble chambers for inertial confinement fusion

NASA Astrophysics Data System (ADS)

Ghilea, Marian C.

One of the main methods to obtain energy from controlled thermonuclear fusion is inertial confinement fusion (ICF), a process where nuclear fusion reactions are initiated by heating and compressing a fuel target, typically in the form of a pellet that contains deuterium and tritium, relying on the inertia of the fuel mass to provide confinement. In inertial confinement fusion experiments, it is important to distinguish failure mechanisms of the imploding capsule and unambiguously diagnose compression and hot spot formation in the fuel. Neutron imaging provides such a technique and bubble chambers are capable of generating higher resolution images than other types of neutron detectors. This thesis explores the use of a liquid bubble chamber to record high yield 14.1 MeV neutrons resulting from deuterium-tritium fusion reactions on ICF experiments. A design tool to deconvolve and reconstruct penumbral and pinhole neutron images was created, using an original ray tracing concept to simulate the neutron images. The design tool proved that misalignment and aperture fabrication errors can significantly decrease the resolution of the reconstructed neutron image. A theoretical model to describe the mechanism of bubble formation was developed. A bubble chamber for neutron imaging with Freon 115 as active medium was designed and implemented for the OMEGA laser system. High neutron yields resulting from deuterium-tritium capsule implosions were recorded. The bubble density was too low for neutron imaging on OMEGA but agreed with the model of bubble formation. The research done in here shows that bubble detectors are a promising technology for the higher neutron yields expected at National Ignition Facility (NIF).

Controlling the Mobility of the Fluid Interface of Moving Gas Bubbles or Liquid Drops by Using Micellar Solutions of Surfactants

NASA Technical Reports Server (NTRS)

Maldarelli, Charles; Papageorgiou, Demetrios

1998-01-01

Microgravity processes must rely on mechanisms other than buoyancy to move bubbles or droplets from one region to another in a continuous liquid phase. One suggested method is thermocapillary migration in which a temperature gradient is applied to the continuous phase. A significant and as yet unresolved impediment to the use of thermocapillary migration to direct bubble or drop motion is that these migrations can be significantly retarded by the adsorption onto the fluid particle surface of surface active impurities unavoidably present in the continuous or (if the particle is a liquid) droplet phases. The focus of our research was to develop a theory for remobilizing fluid particle interfaces retarded by a surfactant impurity in an effort to make more viable the use of thermocapillary migrations for the management of bubbles and drops in microgravity. We postulated that a surfactant at high bulk concentration which kinetically exchanges rapidly with the surface can restore interface mobility. The scaling arguments along with a discussion of the previous literature is reviewed in the context of the scaling framework. The specific objectives of the research were twofold. The first was to prove the remobilization theory by studying a model problem. As the mechanism for remobilization is independent of the force which drives the particle, the fluid particle shape and the presence of fluid inertia, we chose the simplest model consisting of a spherical bubble rising steadily by buoyancy in creeping flow. We solved the hydrodynamic and surfactant transport equations for rapid kinetic exchange to demonstrate that as the concentration increases, the Marangoni retardation at first increases (the low k behavior) and then decreases (the high k behavior). The second objective was to develop a method to determine the kinetic rate constants of a surfactant molecule, since this information is necessary to select surfactants which will exchange rapidly enough relative to the convective rate in the thermocapillary process of interest. To measure the kinetic rate, we measure the dynamic tension change accompanying adsorption onto an initially clean interface, or the re-equilibration in tension when an equilibrium interface is compressed. The dynamic tension measurements are made by a pendant bubble method, in which surfactant adsorbs onto a pendant bubble, and the tension is measured by analyzing the shape change in the bubble. We conclude this report by detailing the publications, presentations and doctoral thesis completed under the auspices of this grant.

Lattice Boltzmann Study of Bubbles on a Patterned Superhydrophobic Surface under Shear Flow

NASA Astrophysics Data System (ADS)

Chen, Wei; Wang, Kai; Hou, Guoxiang; Leng, Wenjun

2018-01-01

This paper studies shear flow over a 2D patterned superhydrophobic surface using lattice Boltzmann method (LBM). Single component Shan-Chen multiphase model and Carnahan-Starling EOS are adopted to handle the liquid-gas flow on superhydrophobic surface with entrapped micro-bubbles. The shape of bubble interface and its influence on slip length under different shear rates are investigated. With increasing shear rate, the bubble interface deforms. Then the contact lines are depinned from the slot edges and move downstream. When the shear rate is high enough, a continuous gas layer forms. If the protrusion angle is small, the gas layer forms and collapse periodically, and accordingly the slip length changes periodically. While if the protrusion angle is large, the gas layer is steady and separates the solid wall from liquid, resulting in a very large slip length.

Iridium-catalyst-based autonomous bubble-propelled graphene micromotors with ultralow catalyst loading.

PubMed

Wang, Hong; Sofer, Zdeněk; Eng, Alex Yong Sheng; Pumera, Martin

2014-11-10

A novel concept of an iridium-based bubble-propelled Janus-particle-type graphene micromotor with very high surface area and with very low catalyst loading is described. The low loading of Ir catalyst (0.54 at %) allows for fast motion of graphene microparticles with high surface area of 316.2 m(2)  g(-1). The micromotor was prepared with a simple and scalable method by thermal exfoliation of iridium-doped graphite oxide precursor composite in hydrogen atmosphere. Oxygen bubbles generated from the decomposition of hydrogen peroxide at the iridium catalytic sites provide robust propulsion thrust for the graphene micromotor. The high surface area and low iridium catalyst loading of the bubble-propelled graphene motors offer great possibilities for dramatically enhanced cargo delivery. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Robust laser-structured asymmetrical PTFE mesh for underwater directional transportation and continuous collection of gas bubbles

NASA Astrophysics Data System (ADS)

Yin, Kai; Yang, Shuai; Dong, Xinran; Chu, Dongkai; Duan, Ji-An; He, Jun

2018-06-01

We report a simple, efficient method to fabricate micro/nanoscale hierarchical structures on one side of polytetrafluoroethylene mesh surfaces, using one-step femtosecond laser direct writing technology. The laser-treated surface exhibits superhydrophobicity in air and superaerophilicity in water, resulting in the mesh possessing the hydrophobic/superhydrophobic asymmetrical property. Bubbles can pass through the mesh from the untreated side to the laser-treated side but cannot pass through the mesh in the opposite direction. The asymmetrical mesh can therefore be designed for the directional transportation and continuous collection of gas bubbles in aqueous environments. Furthermore, the asymmetrical mesh shows excellent stability during corrosion and abrasion tests. These findings may provide an efficient route for fabricating a durable asymmetrical mesh for the directional and continuous transport of gas bubbles.

Inside a Collapsing Bubble: Sonoluminescence and the Conditions During Cavitation

NASA Astrophysics Data System (ADS)

Suslick, Kenneth S.; Flannigan, David J.

2008-05-01

Acoustic cavitation, the growth and rapid collapse of bubbles in a liquid irradiated with ultrasound, is a unique source of energy for driving chemical reactions with sound, a process known as sonochemistry. Another consequence of acoustic cavitation is the emission of light [sonoluminescence (SL)]. Spectroscopic analyses of SL from single bubbles as well as a cloud of bubbles have revealed line and band emission, as well as an underlying continuum arising from a plasma. Application of spectrometric methods of pyrometry as well as tools of plasma diagnostics to relative line intensities, profiles, and peak positions have allowed the determination of intracavity temperatures and pressures. These studies have shown that extraordinary conditions (temperatures up to 20,000 K; pressures of several thousand bar; and heating and cooling rates of >1012 K s1) are generated within an otherwise cold liquid.

Americans Missing in Southeast Asia: Perceptions, Politics, and Realities

DTIC Science & Technology

1990-05-08

large segment of the American electorate and the U.S. Government. The rescue of Americans in captivity or the recovery ,, , 1473 EDITON OF I NOV 65 IS...subsequent identification of Americans who died in captivity , crashes, or battlefield incidents was a by-product of the ad hoc formalization of the...electorate and the U.S. Government. The rescue of Americans in captivity or the recovery and subsequent identification of Americans who died in captivity

Blood chemistry and hematocrit of captive and wild canvasbacks

USGS Publications Warehouse

Perry, M.C.; Obrecht, H.H.; Williams, B.K.; Kuenzel, W.J.

1986-01-01

Blood chemistry and packed cell volume (PCV) did not vary among groups of captive canvasbacks (Aythya valisineria) maintained ad libitum on 5 diets varying in metabolizable energy (ME) and protein. Ducks fed low quality diets increased their consumption so that all ducks were obtaining similar amounts of energy and protein. Some variables, including cholesterol, were found to differ between the sexes and ages of captive ducks. Seasonal differences were detected in the blood chemistry of captive canvasbacks. Four of the 5 enzyme values increased from October to January and then declined to April. PCV increased from 45 in October to 51 in April. Overall, blood chemistry values and PCV's were highly variable and did not appear to be good discriminators for age, sex, and diet of captive canvasbacks. Differences detected between captive and wild canvasbacks were attributed to increased stress of wild ducks during handling.

Characterization of fission gas bubbles in irradiated U-10Mo fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casella, Andrew M.; Burkes, Douglas E.; MacFarlan, Paul J.

2017-09-01

Irradiated U-10Mo fuel samples were prepared with traditional mechanical potting and polishing methods with in a hot cell. They were then removed and imaged with an SEM located outside of a hot cell. The images were then processed with basic imaging techniques from 3 separate software packages. The results were compared and a baseline method for characterization of fission gas bubbles in the samples is proposed. It is hoped that through adoption of or comparison to this baseline method that sample characterization can be somewhat standardized across the field of post irradiated examination of metal fuels.

Refining Reproductive Parameters for Modelling Sustainability and Extinction in Hunted Primate Populations in the Amazon

PubMed Central

Bowler, Mark; Anderson, Matt; Montes, Daniel; Pérez, Pedro; Mayor, Pedro

2014-01-01

Primates are frequently hunted in Amazonia. Assessing the sustainability of hunting is essential to conservation planning. The most-used sustainability model, the ‘Production Model’, and more recent spatial models, rely on basic reproductive parameters for accuracy. These parameters are often crudely estimated. To date, parameters used for the Amazon’s most-hunted primate, the woolly monkey (Lagothrix spp.), come from captive populations in the 1960s, when captive births were rare. Furthermore, woolly monkeys have since been split into five species. We provide reproductive parameters calculated by examining the reproductive organs of female Poeppig’s woolly monkeys (Lagothrix poeppigii), collected by hunters as part of their normal subsistence activity. Production was 0.48–0.54 young per female per year, and an interbirth interval of 22.3 to 25.2 months, similar to parameters from captive populations. However, breeding was seasonal, which imposes limits on the maximum reproductive rate attainable. We recommend the use of spatial models over the Production Model, since they are less sensitive to error in estimated reproductive rates. Further refinements to reproductive parameters are needed for most primate taxa. Methods like ours verify the suitability of captive reproductive rates for sustainability analysis and population modelling for populations under differing conditions of hunting pressure and seasonality. Without such research, population modelling is based largely on guesswork. PMID:24714614

Proposal of a taste evaluating method of the sponge cake by using 3D range sensor

NASA Astrophysics Data System (ADS)

Kato, Kunihito; Yamamoto, Kazuhiko; Ogawa, Noriko

2002-10-01

Nowadays, the image processing techniques are while applying to the food industry in many situations. The most of these researches are applications for the quality control in plants, and there are hardly any cases of measuring the 'taste'. We are developing the measuring system of the deliciousness by using the image sensing. In this paper, we propose the estimation method of the deliciousness of a sponge cake. Considering about the deliciousness of the sponge cake, if the size of the bubbles on the surface is small and the number of them is large, then it is defined that the deliciousness of the sponge cake is better in the field of the food science. We proposed a method of detection bubbles in the surface of the sectional sponge cake automatically by using 3-D image processing. By the statistical information of these detected bubbles based on the food science, the deliciousness is estimated.

Homogenate-assisted Vacuum-powered Bubble Extraction of Moso Bamboo Flavonoids for On-line Scavenging Free Radical Capacity Analysis.

PubMed

Sun, Yinnan; Yang, Kui; Cao, Qin; Sun, Jinde; Xia, Yu; Wang, Yinhang; Li, Wei; Ma, Chunhui; Liu, Shouxin

2017-07-11

A homogenate-assisted vacuum-powered bubble extraction (HVBE) method using ethanol was applied for extraction of flavonoids from Phyllostachys pubescens (P. pubescens) leaves. The mechanisms of homogenate-assisted extraction and vacuum-powered bubble generation were discussed in detail. Furthermore, a method for the rapid determination of flavonoids by HPLC was established. HVBE followed by HPLC was successfully applied for the extraction and quantification of four flavonoids in P. pubescens , including orientin, isoorientin, vitexin, and isovitexin. This method provides a fast and effective means for the preparation and determination of plant active components. Moreover, the on-line antioxidant capacity, including scavenging positive ion and negative ion free radical capacity of different fractions from the bamboo flavonoid extract was evaluated. Results showed that the scavenging DPPH ˙ free radical capacity of vitexin and isovitexin was larger than that of isoorientin and orientin. On the contrary, the scavenging ABTS⁺ ˙ free radical capacity of isoorientin and orientin was larger than that of vitexin and isovitexin.

Non-Contact Temperature Requirements (NCTM) for drop and bubble physics

NASA Technical Reports Server (NTRS)

Hmelo, Anthony B.; Wang, Taylor G.

1989-01-01

Many of the materials research experiments to be conducted in the Space Processing program require a non-contaminating method of manipulating and controlling weightless molten materials. In these experiments, the melt is positioned and formed within a container without physically contacting the container's wall. An acoustic method, which was developed by Professor Taylor G. Wang before coming to Vanderbilt University from the Jet Propulsion Laboratory, has demonstrated the capability of positioning and manipulating room temperature samples. This was accomplished in an earth-based laboratory with a zero-gravity environment of short duration. However, many important facets of high temperature containerless processing technology have not been established yet, nor can they be established from the room temperature studies, because the details of the interaction between an acoustic field an a molten sample are largely unknown. Drop dynamics, bubble dynamics, coalescence behavior of drops and bubbles, electromagnetic and acoustic levitation methods applied to molten metals, and thermal streaming are among the topics discussed.

Differential distribution of sperm subpopulations and incidence of pleiomorphisms in ejaculates of captive howling monkeys ( Alouatta caraya)

NASA Astrophysics Data System (ADS)

Valle, R. R.; Carvalho, F. M.; Muniz, J. A. P. C.; Leal, C. L. V.; García-Herreros, M.

2013-10-01

The aim of this study was to develop an objective method to determine the incidence of pleiomorphisms and its influence on the distribution of sperm morphometric subpopulations in ejaculates of howling monkeys ( Alouatta caraya) by using a combination of computerized analysis system (ASMA) and principal component analysis (PCA) methods. Ejaculates were collected by electroejaculation methods on a regular basis from five individuals maintained under identical captive environmental, nutritional, and management conditions. Each sperm head was measured for dimensional parameters (Area [ A, (square micrometers)], Perimeter [ P, (micrometers)], Length [ L, (micrometers)], and Width [ W, (micrometers)]) and shape-derived parameters (Ellipticity [( L/ W)], Elongation [( L - W)/( L + W)], and Rugosity [(4л A/ P 2)]). PCA revealed two principal components explaining more than the 96 % of the variance. Clustering methods and discriminant analyzes were performed and seven separate subpopulations were identified. There were differences ( P < 0.001) in the distribution of the seven subpopulations as well as in the incidence of abnormal pleiomorphisms (58.6 %, 49.8 %, 35.1 %, 66.4 %, and 55.1 %, P < 0.05) among the five donors tested. Our results indicated that differences among individuals related to the incidence of pleiomorphisms, and sperm subpopulational structure was not related to the captivity conditions or the sperm collection method, since all individuals were studied under identical conditions. In conclusion, the combination of ASMA and PCA is a useful clinical diagnostic resource for detecting deficiencies in sperm morphology and sperm subpopulations in A. caraya ejaculates that could be used in ex situ conservation programs of threatened species in Alouatta genus or even other endangered neotropical primate species.

Cylindrical effects on Richtmyer-Meshkov instability for arbitrary Atwood numbers in weakly nonlinear regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, W. H.; He, X. T.; LCP, Institute of Applied Physics and Computational Mathematics, Beijing 100088

2012-07-15

When an incident shock collides with a corrugated interface separating two fluids of different densities, the interface is prone to Richtmyer-Meshkov instability (RMI). Based on the formal perturbation expansion method as well as the potential flow theory, we present a simple method to investigate the cylindrical effects in weakly nonlinear RMI with the transmitted and reflected cylindrical shocks by considering the nonlinear corrections up to fourth order. The cylindrical results associated with the material interface show that the interface expression consists of two parts: the result in the planar system and that from the cylindrical effects. In the limit ofmore » the cylindrical radius tending to infinity, the cylindrical results can be reduced to those in the planar system. Our explicit results show that the cylindrical effects exert an inward velocity on the whole perturbed interface, regardless of bubbles or spikes of the interface. On the one hand, outgoing bubbles are constrained and ingoing spikes are accelerated for different Atwood numbers (A) and mode numbers k'. On the other hand, for ingoing bubbles, when |A|k'{sup 3/2} Less-Than-Or-Equivalent-To 1, bubbles are considerably accelerated especially at the small |A| and k'; otherwise, bubbles are decelerated. For outgoing spikes, when |A|k' Greater-Than-Or-Equivalent-To 1, spikes are dramatically accelerated especially at large |A| and k'; otherwise, spikes are decelerated. Furthermore, the cylindrical effects have a significant influence on the amplitudes of the ingoing spike and bubble for large k'. Thus, it should be included in applications where the cylindrical effects play a role, such as inertial confinement fusion ignition target design.« less

Limitations of captive breeding in endangered species recovery

USGS Publications Warehouse

Snyder, N.F.R.; Derrickson, S.R.; Beissenger, S.R.; Wiley, J.W.; Smith, T.B.; Toone, W.D.; Miller, B.

1996-01-01

The use of captive breeding in species recovery has grown enormously in recent years, but without a concurrent growth in appreciation of its limitations. Problems with (1) establishing self-sufficient captive populations, (2) poor success in reintroductions, (3.) high costs, (4) domestication, (5) preemption of other recovery techniques, (6) disease outbreaks, and (7) maintaining administrative continuity have all been significant. The technique has often been invoked prematurely and should not normally be employed before a careful field evaluation of costs and benefits of all conservation alternatives has been accomplished and a determination made that captive breeding is essential for species survival. Merely demonstrating that a species population is declining or bas fallen below what may be a minimum viable size does not constitute enough analysis to justify captive breeding as a recovery measure. Captive breeding should be reviewed as a last resort in species recovery and not a prophylactic or long-term solution because of the inexorable genetic and phenotypic changes that occur in captive environments. Captive breeding can play a crucial role in recovery of some species for witch effective alternatives are unavailable in the short term. However, it should not displace habitat and ecosystem protection nor should it be invoked in the absence of comprehensive efforts to maintain or restore populations in wild habitats. Zoological institutions with captive breeding programs should operate under carefully defined conditions of disease prevention and genetic/behavioral management. More important, these institutions should help preserve biodiversity through their capacities for public education, professional training, research, and support of in situ conservation efforts.

Rapid genetic and morphologic divergence between captive and wild populations of the endangered Leon Springs pupfish, Cyprinodon bovinus.

PubMed

Black, Andrew N; Seears, Heidi A; Hollenbeck, Christopher M; Samollow, Paul B

2017-04-01

The Leon Springs pupfish (Cyprinodon bovinus) is an endangered species currently restricted to a single desert spring and a separate captive habitat in southwestern North America. Following establishment of the captive population from wild stock in 1976, the wild population has undergone natural population size fluctuations, intentional culling to purge genetic contamination from an invasive congener (Cyprinodon variegatus) and augmentation/replacement of wild fish from the captive stock. A severe population decline following the most recent introduction of captive fish prompted us to examine whether the captive and wild populations have differentiated during the short time they have been isolated from one another. If so, the development of divergent genetic and/or morphologic traits between populations could contribute to a diminished ability of fish from one location to thrive in the other. Examination of genomewide single nucleotide polymorphisms and morphologic variation revealed no evidence of residual C. variegatus characteristics in contemporary C. bovinus samples. However, significant genetic and morphologic differentiation was detected between the wild and captive populations, some of which might reflect local adaptation. Our results indicate that genetic and physical characteristics can diverge rapidly between isolated subdivisions of managed populations, potentially compromising the value of captive stock for future supplementation efforts. In the case of C. bovinus, our findings underscore the need to periodically inoculate the captive population with wild genetic material to help mitigate genetic, and potentially morphologic, divergence between them and also highlight the utility of parallel morphologic and genomic evaluation to inform conservation management planning. © 2017 John Wiley & Sons Ltd.

Behavioral profiles of the captive juvenile whooping crane as an indicator of post-release survival

USGS Publications Warehouse

Kreger, M.D.; Hatfield, J.S.; Estevez, I.; Gee, G.F.; Clugston, D.A.

2006-01-01

Predation by bobcats (Lynx rufus) is the major cause of mortality in captive-reared whooping cranes (Grus americana) released into the wild to establish a nonmigratory flock in Florida. This study investigated whether rearing methods (parent-rearing, hand-rearing, or hand-rearing with exercise) of cranes, and behaviors observed in birds either before or shortly after release in the wild, are associated with survival after release. Rearing methods did not affect survival first year post-release, which was 55 ? 8% in 2 yr (1999 and 2000). Logistic regression revealed, however, that foraging bouts (+), walking bouts (-), and body weight (-) before release, and nonvigilant bouts (-) after release were significantly associated with survival. These results suggest that post-release survival of whooping cranes might be increased by rearing techniques that promote foraging.

1. CAPTIVE TEST STAND D1 FROM THE FERROCEMENT APRON, VIEW ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. CAPTIVE TEST STAND D-1 FROM THE FERROCEMENT APRON, VIEW TOWARDS SOUTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

2. CLOSE UP OF CAPTIVE TEST STAND D4, VIEW TOWARDS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. CLOSE UP OF CAPTIVE TEST STAND D-4, VIEW TOWARDS NORTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-4, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

1. CAPTIVE TEST STAND D4, CONNECTING TUNNELS AT RIGHT, VIEW ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. CAPTIVE TEST STAND D-4, CONNECTING TUNNELS AT RIGHT, VIEW TOWARDS NORTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-4, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

Experimental studies of contact angle hysteresis phenomena on polymer surfaces – Toward the understanding and control of wettability for different applications.

PubMed

Grundke, K; Pöschel, K; Synytska, A; Frenzel, R; Drechsler, A; Nitschke, M; Cordeiro, A L; Uhlmann, P; Welzel, P B

2015-08-01

Contact angle hysteresis phenomena on polymer surfaces have been studied by contact angle measurements using sessile liquid droplets and captive air bubbles in conjunction with a drop shape method known as Axisymmetric Drop Shape Analysis - Profile (ADSA-P). In addition, commercially available sessile drop goniometer techniques were used. The polymer surfaces were characterized with respect to their surface structure (morphology, roughness, swelling) and surface chemistry (elemental surface composition, acid-base characteristics) by scanning electron microscopy (SEM), scanning force microscopy (SFM), ellipsometry, X-ray photoelectron spectroscopy (XPS) and streaming potential measurements. Heterogeneous polymer surfaces with controlled roughness and chemical composition were prepared by different routes using plasma etching and subsequent dip coating or grafting of polymer brushes, anodic oxidation of aluminium substrates coated with thin polymer films, deposition techniques to create regular patterned and rough fractal surfaces from core-shell particles, and block copolymers. To reveal the effects of swelling and reorientation at the solid/liquid interface contact angle hysteresis phenomena on polyimide surfaces, cellulose membranes, and thermo-responsive hydrogels have been studied. The effect of different solutes in the liquid (electrolytes, surfactants) and their impact on contact angle hysteresis were characterized for solid polymers without and with ionizable functional surface groups in aqueous electrolyte solutions of different ion concentrations and pH and for photoresist surfaces in cationic aqueous surfactant solutions. The work is an attempt toward the understanding of contact angle hysteresis phenomena on polymer surfaces aimed at the control of wettability for different applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Clinical Evaluation of Different Pre-impression Preparation Procedures of Dental Arch

PubMed Central

Arora, Nitin; Arora, Monika; Gupta, Naveen; Agarwal, Manisha; Verma, Rohit; Rathod, Pankaj

2015-01-01

Background: Bubbles and voids on the occlusal surface impede the actual intercuspation and pre-impression preparation aims to reduce the incidence of air bubbles and voids as well as influences the quality of occlusal reproduction and actual clinical intercuspation in the articulator. The study was undertaken to determine the influence of different pre-impression preparation procedures of antagonistic dental arch on the quality of the occlusal reproduction of the teeth in irreversible hydrocolloid impressions and to determine most reliable pre-impression preparation method to reduce the incidence of air bubbles. Materials and Methods: A total of 20 subjects were selected having full complement of mandibular teeth from second molar to second molar with well demarcated cusp height. 200 impressions were made with irreversible hydrocolloid material. The impressions were divided into five groups of 40 impressions each and each group had one specific type of pre-impression preparation. All the impressions were poured in die stone. A stereomicroscope with graduated eyepiece was used to count the number of bubbles on the occlusal surface of premolars and molars. The mean and standard deviations were calculated for each group. Mann–Whitney U-test was applied to find the significant difference between different groups. Results: Least bubbles were found in the group in which oral cavity was dried by saliva ejector and fluid hydrocolloid was finger painted onto the occlusal surfaces immediately before the placement of impression tray in the mouth. Conclusion: It was found that finger painting the tooth surfaces with fluid hydrocolloid immediately before the placement of loaded impression tray in the mouth was the most reliable method. The oral cavity can be cleared more easily of excess saliva by vacuum suction rather than by use of an astringent solution. PMID:26229376

Advanced readout methods for superheated emulsion detectors

NASA Astrophysics Data System (ADS)

d'Errico, F.; Di Fulvio, A.

2018-05-01

Superheated emulsions develop visible vapor bubbles when exposed to ionizing radiation. They consist in droplets of a metastable liquid, emulsified in an inert matrix. The formation of a bubble cavity is accompanied by sound waves. Evaporated bubbles also exhibit a lower refractive index, compared to the inert gel matrix. These two physical phenomena have been exploited to count the number of evaporated bubbles and thus measure the interacting radiation flux. Systems based on piezoelectric transducers have been traditionally used to acquire the acoustic (pressure) signals generated by bubble evaporation. Such systems can operate at ambient noise levels exceeding 100 dB; however, they are affected by a significant dead time (>10 ms). An optical readout technique relying on the scattering of light by neutron-induced bubbles has been recently improved in order to minimize measurement dead time and ambient noise sensitivity. Beams of infra-red light from light-emitting diode (LED) sources cross the active area of the detector and are deflected by evaporated bubbles. The scattered light correlates with bubble density. Planar photodiodes are affixed along the detector length in optimized positions, allowing the detection of scattered light from the bubbles and minimizing the detection of direct light from the LEDs. A low-noise signal-conditioning stage has been designed and realized to amplify the current induced in the photodiodes by scattered light and to subtract the background signal due to intrinsic scattering within the detector matrix. The proposed amplification architecture maximizes the measurement signal-to-noise ratio, yielding a readout uncertainty of 6% (±1 SD), with 1000 evaporated bubbles in a detector active volume of 150 ml (6 cm detector diameter). In this work, we prove that the intensity of scattered light also relates to the bubble size, which can be controlled by applying an external pressure to the detector emulsion. This effect can be exploited during the readout procedure to minimize shadowing effects between bubbles, which become severe when the latter are several thousands. The detector we used in this work is based on superheated C-318 (octafluorocyclobutane), emulsified in 100 μm ± 10% (1 SD) diameter drops in an inert matrix of approximately 150 ml. The detector was operated at room temperature and ambient pressure.

Time-dependent bubble motion through a liquid filled compliant channel

NASA Astrophysics Data System (ADS)

Halpern, David; Gaver, Donald; Jensen, Oliver

2000-11-01

Pulmonary airway closure occurs when the liquid lining layer occludes the airway and obstructs airflow. Meniscus formation is the result of a surface-tension driven instability within the liquid layer. Airway 'compliant collapse' may result, which leads to tube buckling with airway walls held in apposition. Airway closure is common in premature neonates who do not produce sufficient surfactant and those suffering from emphysema. To model the reopening of a collapsed airway flooded with fluid, we consider the time-dependent motion of an air-bubble driven by a positive bubble pressure Pb through a liquid filled compliant channel. The governing Stokes equations are solved using the boundary element method near the bubble tip, and lubrication theory sufficiently far ahead of the buble where the channel walls have a gentle taper. Results show that for Pb > P_crit, the bubble moves forward and converges to a steady velocity as the airway walls 'peel' open. For Pb < P_crit, no steady solutions are found because fluid continuously accummulates ahead of the bubble tip. This result validates the stability analysis of the previously steady wall peeling solution branch. The impact of the flow field on transport of surfactant and the applied shear and normal stresses on the wall as they relate to pulmonary reopening are also discussed.

Numerical modeling of bubble dynamics in viscoelastic media with relaxation

NASA Astrophysics Data System (ADS)

Warnez, M. T.; Johnsen, E.

2015-06-01

Cavitation occurs in a variety of non-Newtonian fluids and viscoelastic materials. The large-amplitude volumetric oscillations of cavitation bubbles give rise to high temperatures and pressures at collapse, as well as induce large and rapid deformation of the surroundings. In this work, we develop a comprehensive numerical framework for spherical bubble dynamics in isotropic media obeying a wide range of viscoelastic constitutive relationships. Our numerical approach solves the compressible Keller-Miksis equation with full thermal effects (inside and outside the bubble) when coupled to a highly generalized constitutive relationship (which allows Newtonian, Kelvin-Voigt, Zener, linear Maxwell, upper-convected Maxwell, Jeffreys, Oldroyd-B, Giesekus, and Phan-Thien-Tanner models). For the latter two models, partial differential equations (PDEs) must be solved in the surrounding medium; for the remaining models, we show that the PDEs can be reduced to ordinary differential equations. To solve the general constitutive PDEs, we present a Chebyshev spectral collocation method, which is robust even for violent collapse. Combining this numerical approach with theoretical analysis, we simulate bubble dynamics in various viscoelastic media to determine the impact of relaxation time, a constitutive parameter, on the associated physics. Relaxation time is found to increase bubble growth and permit rebounds driven purely by residual stresses in the surroundings. Different regimes of oscillations occur depending on the relaxation time.

High Efficiency Hydrodynamic DNA Fragmentation in a Bubbling System

PubMed Central

Li, Lanhui; Jin, Mingliang; Sun, Chenglong; Wang, Xiaoxue; Xie, Shuting; Zhou, Guofu; van den Berg, Albert; Eijkel, Jan C. T.; Shui, Lingling

2017-01-01

DNA fragmentation down to a precise fragment size is important for biomedical applications, disease determination, gene therapy and shotgun sequencing. In this work, a cheap, easy to operate and high efficiency DNA fragmentation method is demonstrated based on hydrodynamic shearing in a bubbling system. We expect that hydrodynamic forces generated during the bubbling process shear the DNA molecules, extending and breaking them at the points where shearing forces are larger than the strength of the phosphate backbone. Factors of applied pressure, bubbling time and temperature have been investigated. Genomic DNA could be fragmented down to controllable 1–10 Kbp fragment lengths with a yield of 75.30–91.60%. We demonstrate that the ends of the genomic DNAs generated from hydrodynamic shearing can be ligated by T4 ligase and the fragmented DNAs can be used as templates for polymerase chain reaction. Therefore, in the bubbling system, DNAs could be hydrodynamically sheared to achieve smaller pieces in dsDNAs available for further processes. It could potentially serve as a DNA sample pretreatment technique in the future. PMID:28098208

Counter-current thermocapillary migration of bubbles in self-rewetting liquids

NASA Astrophysics Data System (ADS)

Nazareth, R.; Saenz, P.; Sefiane, K.; Kim, J.; Valluri, P.

2016-11-01

In this work, we study the counter-current thermocapillary propulsion of a suspended bubble in the fluid flowing inside a channel subject to an axial temperature gradient when the surface tension dependence on temperature is non-monotonic. We use direct numerical simulations to address the two-phase conservation of mass, momentum and energy with a volume-of-fluid method to resolve the deformable interface. Two distinct regimes of counter-current bubble migration are characterized: i) "exponential decay" where the bubble decelerates rapidly until it comes to a halt at the spatial position corresponding to the minimum surface tension and ii) "sustained oscillations" where the bubble oscillates about the point of minimum surface tension. We illustrate how these sustained oscillations arise at low capillary number O(10-5) and moderate Reynolds number O(10) and, they are dampened by viscosity at lower Reynolds number. These results are in agreement with the experiments by Shanahan and Sefiane (Sci. Rep. 4, 2014). The work was supported by the Science without Borders program from CAPES agency of Brazilian Ministry of Education and the European Commission's Thermapower Project (294905).

Early Onset of Nucleate Boiling on Gas-covered Biphilic Surfaces.

PubMed

Shen, Biao; Yamada, Masayuki; Hidaka, Sumitomo; Liu, Jiewei; Shiomi, Junichiro; Amberg, Gustav; Do-Quang, Minh; Kohno, Masamichi; Takahashi, Koji; Takata, Yasuyuki

2017-05-17

For phase-change cooling schemes for electronics, quick activation of nucleate boiling helps safeguard the electronics components from thermal shocks associated with undesired surface superheating at boiling incipience, which is of great importance to the long-term system stability and reliability. Previous experimental studies show that bubble nucleation can occur surprisingly early on mixed-wettability surfaces. In this paper, we report unambiguous evidence that such unusual bubble generation at extremely low temperatures-even below the boiling point-is induced by a significant presence of incondensable gas retained by the hydrophobic surface, which exhibits exceptional stability even surviving extensive boiling deaeration. By means of high-speed imaging, it is revealed that the consequently gassy boiling leads to unique bubble behaviour that stands in sharp contrast with that of pure vapour bubbles. Such findings agree qualitatively well with numerical simulations based on a diffuse-interface method. Moreover, the simulations further demonstrate strong thermocapillary flows accompanying growing bubbles with considerable gas contents, which is associated with heat transfer enhancement on the biphilic surface in the low-superheat region.

High Efficiency Hydrodynamic DNA Fragmentation in a Bubbling System.

PubMed

Li, Lanhui; Jin, Mingliang; Sun, Chenglong; Wang, Xiaoxue; Xie, Shuting; Zhou, Guofu; van den Berg, Albert; Eijkel, Jan C T; Shui, Lingling

2017-01-18

DNA fragmentation down to a precise fragment size is important for biomedical applications, disease determination, gene therapy and shotgun sequencing. In this work, a cheap, easy to operate and high efficiency DNA fragmentation method is demonstrated based on hydrodynamic shearing in a bubbling system. We expect that hydrodynamic forces generated during the bubbling process shear the DNA molecules, extending and breaking them at the points where shearing forces are larger than the strength of the phosphate backbone. Factors of applied pressure, bubbling time and temperature have been investigated. Genomic DNA could be fragmented down to controllable 1-10 Kbp fragment lengths with a yield of 75.30-91.60%. We demonstrate that the ends of the genomic DNAs generated from hydrodynamic shearing can be ligated by T4 ligase and the fragmented DNAs can be used as templates for polymerase chain reaction. Therefore, in the bubbling system, DNAs could be hydrodynamically sheared to achieve smaller pieces in dsDNAs available for further processes. It could potentially serve as a DNA sample pretreatment technique in the future.