Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Cavitation During Superplastic Forming.

ABSTRACT: Cavitation is the opening of pores during superplastic forming, typically at grain boundary triple points or on second phase grain boundary particles during slip of grain boundaries. Theories for the initiation of cavitation are reviewed. It seems that cavitation is unlikely to occur by processes intrinsic to metals such as dislocation mechanisms or point defect condensation. It is proposed that cavitation can only occur at non-bonded interfaces such as those introduced extrinsically (i.e., from the outside) during the original casting of the metal. These defects, known as oxide bifilms, are naturally introduced during pouring of the liquid metal, and are frozen into the solid, often pushed by dendritic growth into grain boundaries where they are difficult to detect because of their extreme thinness, often measured in nanometres. Their unbonded central interface acts as a crack and can initiate cavitation. Second phase precipitates probably do not nucleate and grow on grain boundaries but grow on bifilms in the boundaries, explaining the apparent association between boundaries, second phase particles and failure initiation. Improved melting and casting techniques can provide metal with reduced or zero bifilm population for which cavitation would not be possible, promising significant improvements in superplastic behaviour.

SUBMITTER: Campbell J

PROVIDER: S-EPMC5448684 | biostudies-other | 2011 Jul

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Factors Affecting Tissue Cavitation during Burst Wave Lithotripsy.

Project description:Burst wave lithotripsy (BWL) is a technology under clinical investigation for non-invasive fragmentation of urinary stones. Under certain ranges of ultrasound exposure parameters, this technology can cause cavitation in tissue leading to renal injury. This study sought to measure the focal pressure amplitude needed to cause cavitation in vivo and determine its consistency in native tissue, in an implanted stone model and under different exposure parameters. The kidneys of eight pigs were exposed to transcutaneous BWL ultrasound pulses. In each kidney, two locations were targeted: the renal sinus and the kidney parenchyma. Each was exposed for 5 min at a set pressure level and parameters, and cavitation was detected using an active cavitation imaging method based on power Doppler ultrasound. The threshold was determined by incrementing the pressure amplitude up or down after each 5-min interval until cavitation occurred/subsided. The pressure thresholds were remeasured postsurgery, targeting an implanted stone or collecting space (in sham). The presence of a stone or sham surgery did not significantly impact the threshold for tissue cavitation. Targeting parenchyma instead of kidney collecting space and lowering the ultrasound pulse repetition frequency both resulted in an increased pressure threshold for cavitation.

| S-EPMC8259501 | biostudies-literature

Cavitation clouds created by shock scattering from bubbles during histotripsy.

Project description:Histotripsy is a therapy that focuses short-duration, high-amplitude pulses of ultrasound to incite a localized cavitation cloud that mechanically breaks down tissue. To investigate the mechanism of cloud formation, high-speed photography was used to observe clouds generated during single histotripsy pulses. Pulses of 5-20 cycles duration were applied to a transparent tissue phantom by a 1-MHz spherically focused transducer. Clouds initiated from single cavitation bubbles that formed during the initial cycles of the pulse, and grew along the acoustic axis opposite the propagation direction. Based on these observations, we hypothesized that clouds form as a result of large negative pressure generated by the backscattering of shockwaves from a single bubble. The positive-pressure phase of the wave inverts upon scattering and superimposes on the incident negative-pressure phase to create this negative pressure and cavitation. The process repeats with each cycle of the incident wave, and the bubble cloud elongates toward the transducer. Finite-amplitude propagation distorts the incident wave such that the peak-positive pressure is much greater than the peak-negative pressure, which exaggerates the effect. The hypothesis was tested with two modified incident waves that maintained negative pressure but reduced the positive pressure amplitude. These waves suppressed cloud formation which supported the hypothesis.

| S-EPMC3206907 | biostudies-other

Characterization of transient cavitation activity during sonochemical modification of magnesium particles.

Project description:Investigation of the cavitation activity during ultrasonic treatment of magnesium particles during nanostructuring has been performed. Cavitation activity is recorded in the continuous mode after switching the ultrasound on with the use of ICA-5DM cavitometer. It has been demonstrated that this characteristic of the cavitation zone may be varied in a wide range of constant output parameters of the generator. The speed and nature of the cavitation activity alteration depended on the concentration of Mg particles in the suspension and the properties of the medium in which the sonochemical treatment has been performed. Three stages of the cavitation area evolution can be distinguished: 1 - the initial increase in cavitation activity, 2 - reaching a maximum with a subsequent decrease, and 3 - reaching the plateau (or the repeated cycles with feedback loops of enlargement/reduction of the cavitation activity). The ultrasonically treated magnesium particles have been characterized by scanning electron microscopy, X-ray diffraction analysis and thermal analysis. Depending on the nature of the dispersed medium the particles can be characterized by the presence of magnesium hydroxide (brucite) and magnesium hydride. It is possible to reach the incorporation of magnesium hydride in the magnesium hydroxide/magnesium matrix by varying the conditions of ultrasonic treatment (duration of treatment, amplitude, dispersed medium etc.). The influence of the magnesium reactivity is also confirmed by the measurements of cavitation activity in organic dispersed media (ethanol, ethylene glycol) and their aqueous mixtures.

| S-EPMC7786532 | biostudies-literature

Interfacial cavitation.

Project description:Cavitation has long been recognized as a crucial predictor, or precursor, to the ultimate failure of various materials, ranging from ductile metals to soft and biological materials. Traditionally, cavitation in solids is defined as an unstable expansion of a void or a defect within a material. The critical applied load needed to trigger this instability -- the critical pressure -- is a lengthscale independent material property and has been predicted by numerous theoretical studies for a breadth of constitutive models. While these studies usually assume that cavitation initiates from defects in the bulk of an otherwise homogeneous medium, an alternative and potentially more ubiquitous scenario can occur if the defects are found at interfaces between two distinct media within the body. Such interfaces are becoming increasingly common in modern materials with the use of multimaterial composites and layer-by-layer additive manufacturing methods. However, a criterion to determine the threshold for interfacial failure, in analogy to the bulk cavitation limit, has yet to be reported. In this work, we fill this gap. Our theoretical model captures a lengthscale independent limit for interfacial cavitation, and is shown to agree with our observations at two distinct lengthscales, via two different experimental systems. To further understand the competition between the two cavitation modes (bulk versus interface), we expand our investigation beyond the elastic response to understand the ensuing unstable propagation of delamination at the interface. A phase diagram summarizes these results, showing regimes in which interfacial failure becomes the dominant mechanism.

| S-EPMC9802248 | biostudies-literature

Walruses produce intense impulse sounds by clap-induced cavitation during breeding displays.

Project description:Male walruses produce some of the longest continuous reproductive displays known among mammals to convey their physical fitness to potential rivals and possibly to potential mates. Here, we document the ability of a captive walrus to produce intense, rhythmic sounds through a non-vocal pathway involving deliberate, regular collision of the fore flippers. High-speed videography linked to an acoustic onset marker revealed sound production through cavitation, with the acoustic impulse generated by each forceful clap exceeding a peak-to-peak sound level of 200 dB re. 1 µPa. This clapping display is in some ways quite similar to the knocking display more commonly associated with walruses in rut but is produced through a very different mechanism and with much higher amplitudes. While this clapping behaviour has not yet been documented in wild individuals, it has been observed among other mature male walruses living in human care. Production of intense sounds through cavitation has previously been documented only in crustaceans but may also be an effective means of sound production for some aquatic mammals.

| S-EPMC8242830 | biostudies-literature

Bnip3 and AIF cooperate to induce apoptosis and cavitation during epithelial morphogenesis.

Project description:Apoptosis is an essential step in cavitation during embryonic epithelial morphogenesis, but its mechanisms are largely unknown. In this paper, we used embryonic stem cell-differentiated embryoid bodies (EBs) as a model and found that Bnip3 (Bcl-2/adenovirus E1B 19-kD interacting protein), a BH3-only proapoptotic protein, was highly up-regulated during cavitation in a hypoxia-dependent manner. Short hairpin RNA silencing of Bnip3 inhibited apoptosis of the core cells and delayed cavitation. We show that the Bnip3 up-regulation was mediated mainly by hypoxia-inducible factor (HIF)-2. Ablation of HIF-2α or HIF-1β, the common β subunit of HIF-1 and -2, suppressed Bnip3 up-regulation and inhibited apoptosis and cavitation. We further show that apoptosis-inducing factor (AIF) cooperated with Bnip3 to promote lumen clearance. Bnip3 silencing in AIF-null EBs nearly blocked apoptosis and cavitation. Moreover, AIF also regulated Bnip3 expression through mitochondrial production of reactive oxygen species and consequent HIF-2α stabilization. These results uncover a mechanism of cavitation through hypoxia-induced apoptosis of the core cells mediated by HIFs, Bnip3, and AIF.

| S-EPMC3392936 | biostudies-literature

Laser-enhanced cavitation during high intensity focused ultrasound: An in vivo study.

Project description:Laser-enhanced cavitation during high intensity focused ultrasound (HIFU) was studied in vivo using a small animal model. Laser light was employed to illuminate the sample concurrently with HIFU radiation. The resulting cavitation was detected with a passive cavitation detector. The in vivo measurements were made under different combinations of HIFU treatment depths, laser wavelengths, and HIFU durations. The results demonstrated that concurrent light illumination during HIFU has the potential to enhance cavitation effect by reducing cavitation threshold in vivo.

| S-EPMC3631212 | biostudies-other

Prkci is required for a non-autonomous signal that coordinates cell polarity during cavitation.

Project description:Polarized epithelia define boundaries, spaces, and cavities within organisms. Cavitation, a process by which multicellular hollow balls or tubes are produced, is typically associated with the formation of organized epithelia. In order for these epithelial layers to form, cells must ultimately establish a distinct apical-basal polarity. Atypical PKCs have been proposed to be required for apical-basal polarity in diverse species. Here we show that while cells null for the Prkci isozyme exhibit some polarity characteristics, they fail to properly segregate apical-basal proteins, form a coordinated ectodermal epithelium, or participate in normal cavitation. A failure to cavitate could be due to an overgrowth of interior cells or to an inability of interior cells to die. Null cells however, do not have a marked change in proliferation rate and are still capable of undergoing cell death, suggesting that alterations in these processes are not the predominant cause of the failed cavitation. Overexpression of BMP4 or EZRIN can partially rescue the phenotype possibly by promoting cell death, polarity, and differentiation. However, neither is sufficient to provide the required cues to generate a polarized epithelium and fully rescue cavitation. Interestingly, when wildtype and Prkci(-/-) ES cells are mixed together, a polarized ectodermal epithelium forms and cavitation is rescued, likely due to the ability of wildtype cells to produce non-autonomous polarity cues. We conclude that Prkci is not required for cells to respond to these cues, though it is required to produce them. Together these findings indicate that environmental cues can facilitate the formation of polarized epithelia and that cavitation requires the proper coordination of multiple basic cellular processes including proliferation, differentiation, cell death, and apical-basal polarization.

| S-EPMC8320528 | biostudies-literature

Investigation on the cavitation characteristic of a novel cylindrical rotational hydrodynamic cavitation reactor.

Project description:Hydrodynamic cavitation reactors are of great promise for the applications of chemical process intensification and water treatment. In this work, a novel cylindrical rotational hydrodynamic cavitation reactor (CRHCR) with rectangular grooves and oblique tooth protrusions on the rotor surface was studied. The three-dimensional characterization of cavitation within the CRHCR was observed from the front and left views by the high-speed camera experiments. Interestingly, a new phenomenon of simultaneous formation of the attached cavitation and shear cavitation was found in the CRHCR. The synergistic effect of attached cavitation and shear cavitation contributes to the enhancement of the cavitation performance of CRHCR. In addition, the evolution of attached cavitation is explored. It is found that attached cavitation forms a trapezoidal-shaped cavitation cloud in the groove, which undergoes three various stages: incipient, development, and collapse. Finally, the pulsation frequency and cavitation intensity of shear cavitation in the chamber were investigated. The results show that the cavitation pulsation frequency is the same at the same rotational speed in the chamber near diverse oblique teeth. As the rotational speed increases, the cavitation pulsation frequency increases linearly. These findings in this paper are of great benefit to understanding the mechanism of the cavitation effect of CRHCR.

| S-EPMC11295464 | biostudies-literature

Characterization of cavitation under ultrasonic horn tip - Proposition of an acoustic cavitation parameter.

Project description:Acoustic cavitation, generated by a piezo-driven transducer, is a commonly used technique in a variety of processes, from homogenization, emulsification, and intensification of chemical reactions to surface cleaning and wastewater treatment. An ultrasonic horn, the most commonly used acoustic cavitation device, creates unique cavitation conditions under the horn tip that depend on various parameters such as the tip diameter, the driving frequency of the horn, its amplitude, and fluid properties. Unlike for hydrodynamic cavitation, the scaling laws for acoustic cavitation are poorly understood. Empirical relationships between cavitation dynamics, ultrasonic horn operating conditions, and fluid properties were found through systematic characterization of cavitation under the tip. Experiments were conducted in distilled water with various sodium chloride salt concentrations under different horn amplitudes, tip geometries, and ambient pressures. Cavitation characteristics were monitored by high-speed (200,000 fps) imaging, and numerous relations were found between operating conditions and cavitation dynamics. The compared results are discussed along with a proposal of a novel acoustic cavitation parameter and its relationship to the size of the cavitation cloud under the horn tip. Similar to the classical hydrodynamic cavitation number, the authors propose for the first time an acoustic cavitation parameter based on experimental results.

| S-EPMC9472072 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data