Ancient supernovas discovered: 10-billion-year-old exploding stars were a source of Earth's iron, researchers say

ScienceDaily (Oct. 7, 2011) — Supernovas -- stars in the process of exploding -- open a window onto the history of the elements of Earth's periodic table as well as the history of the universe. All of those heavier than oxygen were formed in nuclear reactions that occurred during these explosions.

The most ancient explosions, far enough away that their light is reaching us only now, can be difficult to spot. A project spearheaded by Tel Aviv University researchers has uncovered a record-breaking number of supernovas in the Subaru Deep Field, a patch of sky the size of a full moon. Out of the 150 supernovas observed, 12 were among the most distant and ancient ever seen.

The discovery sharpens our understanding of the nature of supernovas and their role in element formation, say study leaders Prof. Dan Maoz, Dr. Dovi Poznanski and Or Graur of TAU's Department of Astrophysics at the Raymond and Beverly Sackler School of Physics and Astronomy. These "thermonuclear" supernovas in particular are a major source of iron in the universe.

The research, which appears in the Monthly Notices of the Royal Astronomical Society this month, was done in collaboration with teams from a number of Japanese and American institutions, including the University of Tokyo, Kyoto University, the University of California Berkeley, and Lawrence Berkeley National Laboratory.

A key element of the universe

Supernovas are nature's "element factories." During these explosions, elements are both formed and flung into interstellar space, where they serve as raw materials for new generations of stars and planets. Closer to home, says Prof. Maoz, "these elements are the atoms that form the ground we stand on, our bodies, and the iron in the blood that flows through our veins." By tracking the frequency and types of supernova explosions back through cosmic time, astronomers can reconstruct the universe's history of element creation.

In order to observe the 150,000 galaxies of the Subaru Deep Field, the team used the Japanese Subaru Telescope in Hawaii, on the 14,000-foot summit of the extinct Mauna Kea volcano. The telescope's light-collecting power, sharp images, and wide field of view allowed the researchers to overcome the challenge of viewing such distant supernovas.

By "staring" with the telescope at the Subaru Deep Field, the faint light of the most distant galaxies and supernovas accumulated over several nights at a time, forming a long and deep exposure of the field. Over the course of observations, the team "caught" the supernovas in the act of exploding, identifying 150 supernovas in all.

Sourcing man's life-blood

According to the team's analysis, thermonuclear type supernovas, also called Type-la, were exploding about five times more frequently 10 billion years ago than they are today. These supernovas are a major source of iron in the universe, the main component of Earth's core and an essential ingredient of the blood in our bodies.

Scientists have long been aware of the "universal expansion," the fact that galaxies are receding from one another. Observations using Type-Ia supernovas as beacons have shown that the expansion is accelerating, apparently under the influence of a mysterious "dark energy" -- the 2011 Nobel Prize in Physics will be awarded to three astronomers for this work. However, the nature of the supernovas themselves is poorly understood. This study improves our understanding by revealing the range of the ages of the stars that explode as Type-Ia supernovas. Eventually, this will enhance their usefulness for studying dark energy and the universal expansion, the researchers explain.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Friends of Tel Aviv University.

Journal Reference:

K. Maguire, M. Sullivan, R. C. Thomas, P. Nugent, D. A. Howell, A. Gal-Yam, I. Arcavi, S. Ben-Ami, S. Blake, J. Botyanszki, C. Buton, J. Cooke, R. S. Ellis, I. M. Hook, M. M. Kasliwal, Y.-C. Pan, R. Pereira, P. Podsiadlowski, A. Sternberg, N. Suzuki, D. Xu, O. Yaron, J. S. Bloom, S. B. Cenko, S. R. Kulkarni, N. Law, E. O. Ofek, D. Poznanski, R. M. Quimby. PTF10ops - a subluminous, normal-width light curve Type Ia supernova in the middle of nowhere. Monthly Notices of the Royal Astronomical Society, 2011; DOI: 10.1111/j.1365-2966.2011.19526.x

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Amazing electrical properties in polymers discovered

ScienceDaily (Sep. 25, 2011) — Crystals and ceramics pale when compared to a material researchers at Oak Ridge National Laboratory discovered that has 10 times their piezoelectric effect, making it suitable for perhaps hundreds of everyday uses.

ORNL's Volker Urban and colleagues at Technical University Aachen in Germany noticed the reverse piezoelectric effect -- defined as creating a mechanical strain by applying an electrical voltage -- while conducting fundamental research on polymers. At first they didn't think about their observations in terms of classic piezoelectric materials, but then they became more curious.

"We thought about comparing the effects that we observed to more 'classic' piezoelectric materials and were surprised by how large the effects were by comparison," said Urban, a member of the Department of Energy lab's Neutron Scattering Science Division.

Until now, scientists did not believe that non-polar polymers were capable of exhibiting any piezoelectric effect, which occurs only in non-conductive materials. This research, however, shows up to 10 times the measured electro-active response as compared to the strongest known piezoelectric materials, typically crystals and ceramics.

"We observed this effect when two different polymer molecules like polystyrene and rubber are coupled as two blocks in a di-block copolymer," Urban said.

Temperature-dependent studies of the molecular structure revealed an intricate balance of the repulsion between the unlike blocks and an elastic restoring force found in rubber. The electric field adds a third force that can shift the intricate balance, leading to the piezoelectric effect.

"The extraordinarily large response could revolutionize the field of electro-active devices," said Urban, who listed a number of examples, including sensors, actuators, energy storage devices, power sources and biomedical devices. Urban also noted that additional potential uses are likely as word of this discovery gets out and additional research is performed.

"Ultimately, we're not sure where this finding will take us, but at the very least it provides a fundamentally new perspective in polymer science," Urban said.

The paper was published recently as the cover article in Advanced Materials. In addition to Urban, other authors are Markus Ruppel and Jimmy Mays of ORNL and Kristin Schmidt of the University of California at Santa Barbara. Authors from Aachen University are Christian Pester, Heiko Schoberth, Clemens Liedel, Patrick van Rijn, Kerstin Schindler, Stephanie Hiltl, Thomas Czubak and Alexander Böker.

Funding for this research was provided by DOE's Office of Science and the German Science Foundation.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by DOE/Oak Ridge National Laboratory.

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Christian W. Pester, Markus Ruppel, Heiko G. Schoberth, Kristin Schmidt, Clemens Liedel, Patrick van Rijn, Kerstin A. Schindler, Stephanie Hiltl, Thomas Czubak, Jimmy Mays, Volker S. Urban, Alexander Böker. Piezoelectric Properties of Non-Polar Block Copolymers. Advanced Materials, 2011; 23 (35): 4047 DOI: 10.1002/adma.201102192

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Amazing electrical properties in polymers discovered

ScienceDaily (Sep. 25, 2011) — Crystals and ceramics pale when compared to a material researchers at Oak Ridge National Laboratory discovered that has 10 times their piezoelectric effect, making it suitable for perhaps hundreds of everyday uses.

ORNL's Volker Urban and colleagues at Technical University Aachen in Germany noticed the reverse piezoelectric effect -- defined as creating a mechanical strain by applying an electrical voltage -- while conducting fundamental research on polymers. At first they didn't think about their observations in terms of classic piezoelectric materials, but then they became more curious.

"We thought about comparing the effects that we observed to more 'classic' piezoelectric materials and were surprised by how large the effects were by comparison," said Urban, a member of the Department of Energy lab's Neutron Scattering Science Division.

Until now, scientists did not believe that non-polar polymers were capable of exhibiting any piezoelectric effect, which occurs only in non-conductive materials. This research, however, shows up to 10 times the measured electro-active response as compared to the strongest known piezoelectric materials, typically crystals and ceramics.

"We observed this effect when two different polymer molecules like polystyrene and rubber are coupled as two blocks in a di-block copolymer," Urban said.

Temperature-dependent studies of the molecular structure revealed an intricate balance of the repulsion between the unlike blocks and an elastic restoring force found in rubber. The electric field adds a third force that can shift the intricate balance, leading to the piezoelectric effect.

"The extraordinarily large response could revolutionize the field of electro-active devices," said Urban, who listed a number of examples, including sensors, actuators, energy storage devices, power sources and biomedical devices. Urban also noted that additional potential uses are likely as word of this discovery gets out and additional research is performed.

"Ultimately, we're not sure where this finding will take us, but at the very least it provides a fundamentally new perspective in polymer science," Urban said.

The paper was published recently as the cover article in Advanced Materials. In addition to Urban, other authors are Markus Ruppel and Jimmy Mays of ORNL and Kristin Schmidt of the University of California at Santa Barbara. Authors from Aachen University are Christian Pester, Heiko Schoberth, Clemens Liedel, Patrick van Rijn, Kerstin Schindler, Stephanie Hiltl, Thomas Czubak and Alexander Böker.

Funding for this research was provided by DOE's Office of Science and the German Science Foundation.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by DOE/Oak Ridge National Laboratory.

Journal Reference:

Christian W. Pester, Markus Ruppel, Heiko G. Schoberth, Kristin Schmidt, Clemens Liedel, Patrick van Rijn, Kerstin A. Schindler, Stephanie Hiltl, Thomas Czubak, Jimmy Mays, Volker S. Urban, Alexander Böker. Piezoelectric Properties of Non-Polar Block Copolymers. Advanced Materials, 2011; 23 (35): 4047 DOI: 10.1002/adma.201102192

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Stardust discovered in far-off planetary systems

ScienceDaily (Sep. 29, 2011) — Searching for extra-solar planets -- which are planets outside of our solar system -- is very popular these days. About 700 planets are known at the moment, a number that is continuously rising due to refined observational techniques. Professor Alexander Krivov and his team of astronomers of the Friedrich Schiller University Jena (Germany) just made a remarkable discovery: the scientists from the Astrophysical Institute were able to establish proof of so-called debris discs around two stars. The debris discs are remnants of the formation of the planets.

"We are dealing with enormous accumulations of chunks of matter which create dust when they collide," Alexander Krivov says. This dust is of greatest importance for the astronomers, because it helps to draw conclusions about the planet formation. There are even two debris discs in our solar system, the asteroid belt and the Kuiper belt amongst whose bodies the dwarf planet Pluto belongs.

What makes the Jena discovery so special is the tremendous distance from our solar system to the stars with the debris discs. "These stars are hundreds of light years away from the Earth," according to Krivov. The particular focus is on TrES-2 in the Draco constellation and XO-5 in the Lynx constellation. Planets orbiting these stars can only be detected with the help of the transit method. It sounds like a simple principle: The night sky is photographed in regular intervals. Special software then checks the brightness of the stars on the images. If, in regular intervals, there are differences in brightness it is likely that a planet passes between the star and its observers.

The astronomers found evidence for the stardust with the help of photometric analysis. At first the characteristics of the stars can be analysed with it. If there are irregularities in the invisible infrared range, they point to the existence of stardust. Krivov says: "The dust is warmed up by the star and radiates heat. We see that radiation curve is above the radiation curve of the star as a clear sign of the existence of stardust."

Professor Krivov draws an impressive comparison for the search of debris discs in the vastness of the universe: it is as if you would detect an ice-cream cooled down to minus 130 degrees with a heat detector in a 5,000 kilometer distance from Jena. Alexander Krivov's team of scientists concentrated its search for debris disc candidates on about 100 known extra-solar systems with transiting planets. Of these systems, they found 52 in the observational results of the US-American space telescope WISE.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Friedrich Schiller University Jena, via AlphaGalileo.

Journal Reference:

A. V. Krivov, M. Reidemeister, S. Fiedler, T. Löhne, R. Neuhäuser. Debris disc candidates in systems with transiting planets. Monthly Notices of the Royal Astronomical Society: Letters, 2011; DOI: 10.1111/j.1745-3933.2011.01133.x

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Stardust discovered in far-off planetary systems

ScienceDaily (Sep. 29, 2011) — Searching for extra-solar planets -- which are planets outside of our solar system -- is very popular these days. About 700 planets are known at the moment, a number that is continuously rising due to refined observational techniques. Professor Alexander Krivov and his team of astronomers of the Friedrich Schiller University Jena (Germany) just made a remarkable discovery: the scientists from the Astrophysical Institute were able to establish proof of so-called debris discs around two stars. The debris discs are remnants of the formation of the planets.

"We are dealing with enormous accumulations of chunks of matter which create dust when they collide," Alexander Krivov says. This dust is of greatest importance for the astronomers, because it helps to draw conclusions about the planet formation. There are even two debris discs in our solar system, the asteroid belt and the Kuiper belt amongst whose bodies the dwarf planet Pluto belongs.

What makes the Jena discovery so special is the tremendous distance from our solar system to the stars with the debris discs. "These stars are hundreds of light years away from the Earth," according to Krivov. The particular focus is on TrES-2 in the Draco constellation and XO-5 in the Lynx constellation. Planets orbiting these stars can only be detected with the help of the transit method. It sounds like a simple principle: The night sky is photographed in regular intervals. Special software then checks the brightness of the stars on the images. If, in regular intervals, there are differences in brightness it is likely that a planet passes between the star and its observers.

The astronomers found evidence for the stardust with the help of photometric analysis. At first the characteristics of the stars can be analysed with it. If there are irregularities in the invisible infrared range, they point to the existence of stardust. Krivov says: "The dust is warmed up by the star and radiates heat. We see that radiation curve is above the radiation curve of the star as a clear sign of the existence of stardust."

Professor Krivov draws an impressive comparison for the search of debris discs in the vastness of the universe: it is as if you would detect an ice-cream cooled down to minus 130 degrees with a heat detector in a 5,000 kilometer distance from Jena. Alexander Krivov's team of scientists concentrated its search for debris disc candidates on about 100 known extra-solar systems with transiting planets. Of these systems, they found 52 in the observational results of the US-American space telescope WISE.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Friedrich Schiller University Jena, via AlphaGalileo.

Journal Reference:

A. V. Krivov, M. Reidemeister, S. Fiedler, T. Löhne, R. Neuhäuser. Debris disc candidates in systems with transiting planets. Monthly Notices of the Royal Astronomical Society: Letters, 2011; DOI: 10.1111/j.1745-3933.2011.01133.x

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Simple method of dealing with harmful radioactive iodine discovered

ScienceDaily (May 24, 2011) — A novel way to immobilise radioactive forms of iodine using a microwave, has been discovered by an expert at the University of Sheffield. Iodine radioisotopes are produced by fission of uranium fuel in a nuclear reactor. Radioactive iodine is of concern because it is highly mobile in the environment and selective uptake by the thyroid gland can pose a significant cancer risk following long term exposure. Furthermore, iodine-129, which is a type of radioactive iodine, has an extremely long half life of 15.7 million years, so is one of the most significant long term hazards faced by the population due to its emission during the geological disposal of nuclear waste.

Professor Neil Hyatt, from the University´s Department of Materials Science and Engineering, has now found a way of locking up iodine radioisotopes in a durable, solid material suitable for ultimate disposal, like lead iodovanadinite(Pb5(VO4)3I). The research, which was published in the Journal of Nuclear Materials, demonstrates how his simple, inexpensive and rapid method can be done at atmospheric pressure.

Professor Hyatt and his team created a solid material for immobilisation of iodine with the formula Pb5(VO4)3I, by heating a mixture of lead iodide, lead oxide and vanadium oxide.

Previously, this has only been achieved using high pressure and a sealed container, because iodine is volatilised at high temperature. However, using the knowledge that vanadium is a good absorber of microwaves at 2.45 GHz -- the frequency used in domestic microwave ovens -- the team were able to heat the mixture of chemicals in a microwave oven to produce Pb5(VO4)3I in about three minutes.

The key to the method´s success is that Pb5(VO4)3I is a poor absorber of 2.45 GHz microwaves, so once this is formed, the sample cannot absorb microwaves, so the temperature does not get high enough for the iodine to volatilise.

Iodine-131 was the harmful gas emitted from the Fukushima power plant in Japan following the earthquake and tsunami last month, and was a significant contributor to the health effects from open-air atomic bomb testing in the 1950s, and was also emitted during the Chernobyl disaster. It is hoped the new research will reduce the public health impact associated with the release of radioactive iodine to the environment by providing a simple and inexpensive method of immobilisation in a solid material, which could be rapidly deployed in an accident scenario.

Professor Neil Hyatt, said: "In spent nuclear fuel, the iodine is not immobilised, so once the containment is breached it simply gets dispersed. At present, iodine-129 released by nuclear fuel reprocessing is discharged direct to the Irish Sea off the coast of Sellafield. Substantial quantities of this radioisotope were also released into the sea off the coast of Japan in the Fukushima incident. Our new method offers a way of safely and rapidly containing this radionuclide, reducing the potential long term impact on human health from discharge to the environment."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Sheffield.

Journal Reference:

M.C. Stennett, I.J. Pinnock, N.C. Hyatt. Rapid synthesis of Pb5(VO4)3I, for the immobilisation of iodine radioisotopes, by microwave dielectric heating. Journal of Nuclear Materials, 2011; DOI: 10.1016/j.jnucmat.2011.04.041

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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Simple method of dealing with harmful radioactive iodine discovered

ScienceDaily (May 24, 2011) — A novel way to immobilise radioactive forms of iodine using a microwave, has been discovered by an expert at the University of Sheffield. Iodine radioisotopes are produced by fission of uranium fuel in a nuclear reactor. Radioactive iodine is of concern because it is highly mobile in the environment and selective uptake by the thyroid gland can pose a significant cancer risk following long term exposure. Furthermore, iodine-129, which is a type of radioactive iodine, has an extremely long half life of 15.7 million years, so is one of the most significant long term hazards faced by the population due to its emission during the geological disposal of nuclear waste.

Professor Neil Hyatt, from the University´s Department of Materials Science and Engineering, has now found a way of locking up iodine radioisotopes in a durable, solid material suitable for ultimate disposal, like lead iodovanadinite(Pb5(VO4)3I). The research, which was published in the Journal of Nuclear Materials, demonstrates how his simple, inexpensive and rapid method can be done at atmospheric pressure.

Professor Hyatt and his team created a solid material for immobilisation of iodine with the formula Pb5(VO4)3I, by heating a mixture of lead iodide, lead oxide and vanadium oxide.

Previously, this has only been achieved using high pressure and a sealed container, because iodine is volatilised at high temperature. However, using the knowledge that vanadium is a good absorber of microwaves at 2.45 GHz -- the frequency used in domestic microwave ovens -- the team were able to heat the mixture of chemicals in a microwave oven to produce Pb5(VO4)3I in about three minutes.

The key to the method´s success is that Pb5(VO4)3I is a poor absorber of 2.45 GHz microwaves, so once this is formed, the sample cannot absorb microwaves, so the temperature does not get high enough for the iodine to volatilise.

Iodine-131 was the harmful gas emitted from the Fukushima power plant in Japan following the earthquake and tsunami last month, and was a significant contributor to the health effects from open-air atomic bomb testing in the 1950s, and was also emitted during the Chernobyl disaster. It is hoped the new research will reduce the public health impact associated with the release of radioactive iodine to the environment by providing a simple and inexpensive method of immobilisation in a solid material, which could be rapidly deployed in an accident scenario.

Professor Neil Hyatt, said: "In spent nuclear fuel, the iodine is not immobilised, so once the containment is breached it simply gets dispersed. At present, iodine-129 released by nuclear fuel reprocessing is discharged direct to the Irish Sea off the coast of Sellafield. Substantial quantities of this radioisotope were also released into the sea off the coast of Japan in the Fukushima incident. Our new method offers a way of safely and rapidly containing this radionuclide, reducing the potential long term impact on human health from discharge to the environment."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Sheffield.

Journal Reference:

M.C. Stennett, I.J. Pinnock, N.C. Hyatt. Rapid synthesis of Pb5(VO4)3I, for the immobilisation of iodine radioisotopes, by microwave dielectric heating. Journal of Nuclear Materials, 2011; DOI: 10.1016/j.jnucmat.2011.04.041

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

New properties of supercooled confined water discovered

ScienceDaily (May 12, 2011) — A study led by the UB researcher Giancarlo Franzese and published in the journal Physical Review Letters suggests that hydrophobic nanoconfinement can alter the thermodynamics of water at supercool temperatures. These findings may have important applications in fields related to conservation at cryogenic temperatures (around -100 ºC) -- for example, in the preservation of stem cells, blood and food products.

The team behind the study, led by Giancarlo Franzese from the UB's Department of Fundamental Physics, included researchers from Boston University and TU Berlin.

Water exhibits atypical fluid behaviour. One of its unique characteristics is the increase in heat capacity as water cools, an anomaly that enables us to regulate our body temperature. When water is supercooled -- that is, when it is in liquid state at a temperature below its melting point -- the range of anomalies expands. This irregular behaviour has generated fierce scientific debate over the last twenty years and could hold the key to understanding why water is so different to other liquids and why it is so important for biological organisms.

From a technical perspective, it is difficult to observe supercooled water directly and many researchers opt to use nanoconfinement. In this study, the team used Monte Carlo simulations to study a layer of water only one nanometre high -- approximately equivalent to the diameter of three water molecules -- confined between two hydrophobic plates. Hydrophobic nanoparticles were then added to the water layer in random positions to generate nanochannels or variable size.

This process led to a strong decrease in thermodynamic fluctuations, reflected in compressibility, thermal expansion coefficient and specific heat. The observed decrease occurred at all pressures tested, and at pressures in the region of 180 MPa fluctuations dropped by almost 99% for a concentration in nanoparticles of 25% by volume. The reduction was found to be as high as 90% even at a particle concentration ten times lower.

According to Giancarlo Franzese, the results show that the thermodynamic behaviour of water confined in hydrophobic nanochannels is very different to that of unconfined water, even allowing for the possible presence of more than one liquid phase within the range of temperatures and pressures tested.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Universidad de Barcelona, via AlphaGalileo.

Journal Reference:

Elena Strekalova, Marco Mazza, H. Stanley, Giancarlo Franzese. Large Decrease of Fluctuations for Supercooled Water in Hydrophobic Nanoconfinement. Physical Review Letters, 2011; 106 (14) DOI: 10.1103/PhysRevLett.106.145701

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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New mineral discovered: One of earliest minerals formed in solar system

ScienceDaily (May 7, 2011) — In the May-June issue of the journal American Mineralogist, a team of scientists announced the discovery of the new mineral krotite, one of the earliest minerals formed in our solar system. It is the main component of an unusual inclusion embedded in a meteorite (NWA 1934), found in northwest Africa. These objects, known as refractory inclusions, are thought to be the first planetary materials formed in our solar system, dating back to before the formation of Earth and the other planets.

This particular grain is known affectionately as "Cracked Egg" for its distinctive appearance. Dr. Harold C. Connolly, Jr. and student Stuart A. Sweeney Smith at the City University of New York (CUNY) and the American Museum of Natural History (AMNH) first recognized the grain to be of a very special type, known as a calcium-aluminum-rich refractory inclusion. ("Refractory" refers to the fact that these grains contain minerals that are stable at very high temperature, which attests to their likely formation as very primitive, high-temperature condensates from the solar nebula.)

Cracked Egg refractory inclusion was sent to Dr. Chi Ma at California Institute of Technology (Caltech) for very detailed nano-mineralogy investigation. Dr. Ma then sent it to Dr. Anthony Kampf, Curator of Mineral Sciences at the Natural History Museum of Los Angeles County (NHM), for X- ray diffraction study. Kampf's findings, confirmed by Ma, showed the main component of the grain was a low-pressure calcium aluminum oxide (CaAl2O4) never before found in nature. Kampf's determination of the atomic arrangement in the mineral showed it to be the same as that of a human-made component of some types of refractory (high-temperature) concrete.

What insight can we get from knowing that a common human-made component of modern concrete is found in nature only as a very rare component of a grain formed more than 4.5 billion years ago? Such investigations are essential in deciphering the origins of our solar system. The creation of the human-made compound requires temperature of at least 1,500°C (2,732°F). This, coupled with the fact that the compound forms at low pressure, is consistent with krotite forming as a refractory phase from the solar nebula. Therefore, the likelihood is that krotite is one of the first minerals formed in our solar system.

Studies of the unique Cracked Egg refractory inclusion are continuing, in an effort to learn more about the conditions under which it formed and subsequently evolved. In addition to krotite, the Cracked Egg contains at least eight other minerals, including one other mineral new to science.

The American Mineralogist paper is authored by Chi Ma (Caltech), Anthony R. Kampf (NHM), Harold C. Connolly Jr. (CUNY and AMNH), John R. Beckett (Caltech), George R. Rossman (Caltech), Stuart A. Sweeney Smith (who was a NSF funded Research for Undergraduate (REU) student at CUNY/AMNH) and Devin L. Schrader (University of Arizona). Krotite is named for Alexander N. Krot, a cosmochemist at the University of Hawaii, in recognition of his significant contributions to the understanding of early solar system processes.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Natural History Museum of Los Angeles County.

Journal Reference:

Chi Ma, Anthony R. Kampf, Harold C. Connolly Jr., John R. Beckett, George R. Rossman, Stuart A. Sweeney Smith, and Devin L. Schrader. Krotite, CaAl2O4, a new refractory mineral from the NWA 1934 meteorite. American Mineralogist, 2011; 96: 709-715 [link]

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View the original article here

New properties of supercooled confined water discovered

ScienceDaily (May 12, 2011) — A study led by the UB researcher Giancarlo Franzese and published in the journal Physical Review Letters suggests that hydrophobic nanoconfinement can alter the thermodynamics of water at supercool temperatures. These findings may have important applications in fields related to conservation at cryogenic temperatures (around -100 ºC) -- for example, in the preservation of stem cells, blood and food products.

The team behind the study, led by Giancarlo Franzese from the UB's Department of Fundamental Physics, included researchers from Boston University and TU Berlin.

Water exhibits atypical fluid behaviour. One of its unique characteristics is the increase in heat capacity as water cools, an anomaly that enables us to regulate our body temperature. When water is supercooled -- that is, when it is in liquid state at a temperature below its melting point -- the range of anomalies expands. This irregular behaviour has generated fierce scientific debate over the last twenty years and could hold the key to understanding why water is so different to other liquids and why it is so important for biological organisms.

From a technical perspective, it is difficult to observe supercooled water directly and many researchers opt to use nanoconfinement. In this study, the team used Monte Carlo simulations to study a layer of water only one nanometre high -- approximately equivalent to the diameter of three water molecules -- confined between two hydrophobic plates. Hydrophobic nanoparticles were then added to the water layer in random positions to generate nanochannels or variable size.

This process led to a strong decrease in thermodynamic fluctuations, reflected in compressibility, thermal expansion coefficient and specific heat. The observed decrease occurred at all pressures tested, and at pressures in the region of 180 MPa fluctuations dropped by almost 99% for a concentration in nanoparticles of 25% by volume. The reduction was found to be as high as 90% even at a particle concentration ten times lower.

According to Giancarlo Franzese, the results show that the thermodynamic behaviour of water confined in hydrophobic nanochannels is very different to that of unconfined water, even allowing for the possible presence of more than one liquid phase within the range of temperatures and pressures tested.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Universidad de Barcelona, via AlphaGalileo.

Journal Reference:

Elena Strekalova, Marco Mazza, H. Stanley, Giancarlo Franzese. Large Decrease of Fluctuations for Supercooled Water in Hydrophobic Nanoconfinement. Physical Review Letters, 2011; 106 (14) DOI: 10.1103/PhysRevLett.106.145701

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

New mineral discovered: One of earliest minerals formed in solar system

ScienceDaily (May 7, 2011) — In the May-June issue of the journal American Mineralogist, a team of scientists announced the discovery of the new mineral krotite, one of the earliest minerals formed in our solar system. It is the main component of an unusual inclusion embedded in a meteorite (NWA 1934), found in northwest Africa. These objects, known as refractory inclusions, are thought to be the first planetary materials formed in our solar system, dating back to before the formation of Earth and the other planets.

This particular grain is known affectionately as "Cracked Egg" for its distinctive appearance. Dr. Harold C. Connolly, Jr. and student Stuart A. Sweeney Smith at the City University of New York (CUNY) and the American Museum of Natural History (AMNH) first recognized the grain to be of a very special type, known as a calcium-aluminum-rich refractory inclusion. ("Refractory" refers to the fact that these grains contain minerals that are stable at very high temperature, which attests to their likely formation as very primitive, high-temperature condensates from the solar nebula.)

Cracked Egg refractory inclusion was sent to Dr. Chi Ma at California Institute of Technology (Caltech) for very detailed nano-mineralogy investigation. Dr. Ma then sent it to Dr. Anthony Kampf, Curator of Mineral Sciences at the Natural History Museum of Los Angeles County (NHM), for X- ray diffraction study. Kampf's findings, confirmed by Ma, showed the main component of the grain was a low-pressure calcium aluminum oxide (CaAl2O4) never before found in nature. Kampf's determination of the atomic arrangement in the mineral showed it to be the same as that of a human-made component of some types of refractory (high-temperature) concrete.

What insight can we get from knowing that a common human-made component of modern concrete is found in nature only as a very rare component of a grain formed more than 4.5 billion years ago? Such investigations are essential in deciphering the origins of our solar system. The creation of the human-made compound requires temperature of at least 1,500°C (2,732°F). This, coupled with the fact that the compound forms at low pressure, is consistent with krotite forming as a refractory phase from the solar nebula. Therefore, the likelihood is that krotite is one of the first minerals formed in our solar system.

Studies of the unique Cracked Egg refractory inclusion are continuing, in an effort to learn more about the conditions under which it formed and subsequently evolved. In addition to krotite, the Cracked Egg contains at least eight other minerals, including one other mineral new to science.

The American Mineralogist paper is authored by Chi Ma (Caltech), Anthony R. Kampf (NHM), Harold C. Connolly Jr. (CUNY and AMNH), John R. Beckett (Caltech), George R. Rossman (Caltech), Stuart A. Sweeney Smith (who was a NSF funded Research for Undergraduate (REU) student at CUNY/AMNH) and Devin L. Schrader (University of Arizona). Krotite is named for Alexander N. Krot, a cosmochemist at the University of Hawaii, in recognition of his significant contributions to the understanding of early solar system processes.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Natural History Museum of Los Angeles County.

Journal Reference:

Chi Ma, Anthony R. Kampf, Harold C. Connolly Jr., John R. Beckett, George R. Rossman, Stuart A. Sweeney Smith, and Devin L. Schrader. Krotite, CaAl2O4, a new refractory mineral from the NWA 1934 meteorite. American Mineralogist, 2011; 96: 709-715 [link]

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Anti-helium discovered in Relativistic Heavy Ion Collider experiment

ScienceDaily (Apr. 25, 2011) — Eighteen examples of the heaviest antiparticle ever found, the nucleus of antihelium-4, have been made in the STAR experiment at RHIC, the Relativistic Heavy Ion Collider at the U.S. Department of Energy's Brookhaven National Laboratory.

"The STAR experiment is uniquely capable of finding antihelium-4," says the STAR experiment's spokesperson, Nu Xu, of the Nuclear Science Division (NSD) at Lawrence Berkeley National Laboratory (Berkeley Lab). "STAR already holds the record for massive antiparticles, last year having identified the anti-hypertriton, which contains three constituent antiparticles. With four antinucleons, antihelium-4 is produced at a rate a thousand times lower yet. To identify the 18 examples required sifting through the debris of a billion gold-gold collisions."

Collisions of energetic gold nuclei inside STAR briefly recreate conditions in the hot, dense early universe only millionths of a second after the big bang. Since equal amounts of matter and antimatter were created in the big bang they should have completely annihilated one another, but for reasons still not understood, only ordinary matter seems to have survived. Today this excess matter forms all of the visible universe we know.

Roughly equal amounts of matter and antimatter are also produced in heavy-ion (gold nuclei) collisions at RHIC. The resulting fireballs expand and cool quickly, so the antimatter can avoid annihilation long enough to be detected in the Time Projection Chamber at the heart of STAR.

Ordinary nuclei of helium atoms consist of two protons and two neutrons. Called alpha particles when emitted in radioactive decays, they were found in this form by Ernest Rutherford well over a century ago. The nucleus of antihelium-4 (the anti-alpha) contains two antiprotons bound with two antineutrons.

The most common antiparticles are generally the least massive, because it takes less energy to create them. Carl Anderson was the first to find an antiparticle, the antielectron (positron), in cosmic ray debris 1932. The antiproton (the nucleus of antihydrogen) and the antineutron were created at Berkeley Lab's Bevatron in the 1950s. Antideuteron nuclei ("anti-heavy-hydrogen," made of an antiproton and an antineutron) were created in accelerators at Brookhaven and CERN in the 1960s.

Each extra nucleon (called a baryon) increases the particle's baryon number, and in the STAR collisions every increase in baryon number decreases the rate of yield roughly a thousand times. The nuclei of the antihelium isotope with only one neutron (antihelium-3) has been made in accelerators since 1970; the STAR experiment produces many of these antiparticles, having baryon number 3. The antihelium nucleus with baryon number 4, just announced by STAR based on 16 examples identified in 2010 and two examples from an earlier run, contains the most nucleons of any antiparticle ever detected.

"It's likely that antihelium will be the heaviest antiparticle seen in an accelerator for some time to come," says STAR Collaboration member Xiangming Sun of Berkeley Lab's NSD. "After antihelium the next stable antimatter nucleus would be antilithium, and the production rate for antilithium in an accelerator is expected to be well over two million times less than for antihelium."

NSD's Maxim Naglis adds, "Finding even one example of antilithium would be a stroke of luck, and would probably require a breakthrough in accelerator technology."

If antihelium made by accelerators is rare, and heavier antiparticles rarer still, what of searching for these particles in space? The Alpha Magnetic Spectrometer (AMS) experiment, scheduled to be launched on one of the last space-shuttle missions to the International Space Station, is an instrument designed to do just that. A principal part of its mission is to hunt for distant galaxies made entirely of antimatter.

"Collisions among cosmic rays near Earth can produce antimatter particles, but the odds of these collisions producing an intact antihelium nucleus are so vanishingly small that finding even one would strongly suggest that it had drifted to Earth from a distant region of the universe dominated by antimatter," explains Hans Georg Ritter of Berkeley Lab's NSD. "Antimatter doesn't look any different from ordinary matter, but AMS finding just one antihelium nucleus would suggest that some of the galaxies we see are antimatter galaxies."

Meanwhile the STAR experiment at RHIC, which has shown that antihelium does indeed exist, is likely to hold the world record for finding the heaviest particle of antimatter for the foreseeable future.

This work was supported by the DOE Office of Science.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by DOE/Lawrence Berkeley National Laboratory.

Journal Reference:

H. Agakishiev et al. Observation of the antimatter helium-4 nucleus. Nature, 2011; DOI: 10.1038/nature10079

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