Uncovering liquid foam's bubbly acoustics

First study to show specific sounds' speed and attenuation characteristics in liquid foam

2013-10-17

(Press-News.org) Liquid foams fascinate toddlers singing in a bubble bath. Physicists, too, have an interest in their acoustical properties. Borrowing from both porous material and foam science, Juliette Pierre from the Paris Diderot University, Paris, France and her colleagues studied liquid foams. They used an impedance tube to measure the velocity and attenuation of acoustic waves in liquid foams in a broad frequency range. The study published in EPJ E is a first in the literature. It could help in assessing any liquid foam's bubble size or in designing the optimal foam structure for sound proofing.

The authors used well-characterised liquid foam samples. Thus, they knew all the parameters needed for computing predictions on the acoustics characteristics of existing foam models.

The authors found that the effective velocity of sound in liquid foams is low, ranging from 20 to 60 meters per second. It is lower than the speed of sound in each of its constituents, namely 1,500 and 340 meters per second in water and air, respectively. They also confirmed previous findings: sound velocity only depends on the liquid volume fraction and not on the bubble size over the investigated range of frequencies.

In addition, by looking into several types of liquid foams with the same structure but different composition, they found shaving foam to have a higher effective sound velocity than any other foam. This means that the type of foaming solution influences acoustic properties.

Finally, they showed that the existing models do not give a good prediction of the high sound attenuation observed. The next step would be to understand the influence of the distribution of bubble size and the physicochemical composition of the foam.

### References: J. Pierre et al.(2013), Acoustic characterisation of liquid foams with an impedance tube, European Physical Journal E, 36: 113, DOI 10.1140/epje/i2013-13113-1

For more information visit: http://www.epj.org

The full-text article is available to journalists on request.

ELSE PRESS RELEASES FROM THIS DATE:

Is a constructive conservation the last chance for biodiversity?

2013-10-17

In a human-dominated world that contains only little "historical" nature, the term ecosystem can no longer be a synonym for unspoilt nature. The term "novel ecosystems" was coined a few years ago to describe disturbed ecosystems, in which biodiversity has been significantly altered as the result of human intervention. "In our new conservation framework we argue that this strict distinction between historic and novel ecosystems should be reconsidered to aid conservation", pollination biologist Dr. Christopher Kaiser-Bunbury describes the approach, which is not without controversy. On ...

Transcription factors: Function follows form

2013-10-17

This news release is available in German. Clay can be used in various forms for a range of objects such as cups, plates or bricks. Similarly, proteins can transform their structure and thus adapt their function and activity. Researchers at the Max Planck Institute for Molecular Genetics in Berlin have analysed proteins for such modifications that control gene activity, so-called transcription factors. The researchers thereby discovered that DNA changes the form and the activity of the glucocorticoid receptor, and also ascertained how various domains in the molecule ...

World's first mapping of America's rare plants

2013-10-17

In collaboration with international colleagues, a research group at Aarhus University, Denmark, has contributed to the compilation of the most comprehensive botanical data set to date. PhD student Naia Morueta-Holme and her supervisor, Professor Jens-Christian Svenning, Department of Bioscience, spearheaded the analysis that reveals where rare species are found in the New World (North and South America) and the factors that determine whether a region is dominated by widespread or rare species. "The study shows that especially California, Mexico, the Caribbean islands, ...

CHOP's Harvest toolkit offers innovative data discovery resource for biomedical researchers

2013-10-17

Biomedical researchers often confront large quantities of information that may be amassed in many forms: vital signs, blood cell counts, lengthy DNA sequences, bar graphs, MRIs, patient demographics, and so much more. How do researchers assemble, access and analyze all that data without having to become specialized database technicians themselves? A team of informatics experts and biomedical researchers at The Children's Hospital of Philadelphia (CHOP) offers a new software toolkit to help researchers wrangle data. Their open-source, highly interactive framework called ...

Female doctors are better than male doctors

2013-10-17

According to a University of Montreal research team, the quality of care provided by female doctors is higher than that of their male counterparts while the productivity of males is greater. The research team reached this conclusion by studying the billing information of over 870 Quebec practitioners (half of whom were women) relating to their procedures with elderly diabetic patients. "Women had significantly higher scores in terms of compliance with practice guidelines. They were more likely than men to prescribe recommended medications and to plan required examinations," ...

A Lost Generation of young scientists? U-M grad student voices concern about research funding crunch

2013-10-17

ANN ARBOR, Mich. — Alexis Carulli wants to make a difference in fighting human disease. So do the thousands of bright graduate students like her, and recent Ph.D. graduates, working in medical research laboratories around the country. But with federal scientific research funding flat, eroded by inflation and cut by budget sequestration, Carulli worries for her generation of aspiring biomedical scientists. In a new article published in the American Journal of Physiology: Gastrointestinal and Liver Physiology, she speaks up about it, to make sure the voice of the young ...

3D images generated from PET/CT scans help surgeons envision tumors

2013-10-17

(PHILADELPHIA) Researchers at Jefferson Medical College in Philadelphia have developed a hologram-like display of a patient's organs that surgeons can use to plan surgery. This approach uses molecular PET/CT images of a patient to rapidly create a 3D image of that patient, so that surgeons can see the detailed anatomical structure, peel away layers of tissue, and move around in space to see all sides of a tumor, before entering the operating room to excise it. "Our technology presents PET/CT data in an intuitive manner to help physicians make critical decisions during ...

American Chemical Society podcast: An environmentally friendly battery made from wood

2013-10-17

The latest episode in the American Chemical Society's (ACS') award-winning Global Challenges/Chemistry Solutions podcast series takes its inspiration from trees. It describes the development of a battery made from a sliver of wood coated with tin that shows promise for becoming a tiny, long-lasting, efficient and environmentally friendly energy source. Based on a report by Liangbing Hu, Ph.D., and Teng Li, Ph.D., in ACS' journal Nano Letters, the new podcast is available without charge at iTunes and from http://www.acs.org/globalchallenges. The device is 1,000 times ...

LSUHSC bird study finds key info about human speech-language development

2013-10-17

New Orleans, LA – A study led by Xiaoching Li, PhD, at the LSU Health Sciences Center New Orleans Neuroscience Center of Excellence, has shown for the first time how two tiny molecules regulate a gene implicated in speech and language impairments as well as autism disorders, and that social context of vocal behavior governs their function. The findings are published in the October 16, 2013 issue of The Journal of Neuroscience. Speech and language impairments affect the lives of millions of people, but the underlying neural mechanisms are largely unknown and difficult ...

Weighing up blood-thinners: Is warfarin always the best choice?

2013-10-17

Patients who are responding below par to the anticoagulant drug warfarin have several options. They can undergo even more blood tests to monitor their response to the different dosages of this medication which is prescribed to prevent strokes, or they could start using one of the newer, yet more expensive, anticoagulants on the market. In the long run, says Joyce You of the Chinese University of Hong Kong in China, the latter option could actually be more cost-effective and improve a patient's quality of life. Her study¹ appears in the Journal of General Internal Medicine, ...

Uncovering liquid foam's bubbly acoustics

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: