Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. Space Industry and Business News .




TECH SPACE
Vaterite: Crystal within a crystal helps resolve an old puzzle
by Staff Writers
Madison WI (SPX) Apr 29, 2013


Just 10 micrometers in diameter, the needlelike spicule from the sea squirt Herdmania momus helped researchers in Israel and Wisconsin unlock the crystal structure of vaterite, a geologic and biogenic mineral whose structural secrets have stymied scientists for almost 100 years. Photo: Pupa U. P. A. Gilbert, Lee Kabalah-Amitai, Boaz Pokroy.

With the help of a solitary sea squirt, scientists have resolved the longstanding puzzle of the crystal structure of vaterite, an enigmatic geologic mineral and biomineral.

A form of calcium carbonate, vaterite can be found in Portland cement. Its quick transformation into other more stable forms of calcium carbonate when exposed to water helps make the cement hard and water resistant. As a biomineral, vaterite is found in such things as gallstones, fish otoliths, freshwater pearls, and the healed scars of some mollusk shells.

But unlike most minerals, vaterite has defied every effort to resolve its crystal structure, stymieing scientists for nearly 100 years. The structure of a mineral crystal is a critically important feature and is determined by how atoms are arranged in the crystal. The arrangement of atoms and the resulting crystal structure, for instance, make the difference between graphite and diamond, both forms of pure carbon.

Now, however, a team of scientists from the Technion-Israel Institute of Technology and the University of Wisconsin-Madison has discovered the crystalline secrets of vaterite with the help of a needlelike spicule from a sea squirt found in the Mediterranean and Red Seas.

Writing in the journal Science, a group led by Boaz Pokroy of Technion and Pupa Gilbert of UW-Madison report that vaterite is composed of two different crystal structures that "coexist within a pseudo-single crystal."

"We never envisaged this scenario," explains Pokroy, a professor of materials science and engineering at Technion. "It was a total surprise, but at the same time it made so much sense knowing the years of conflicting results from different groups publishing on the structure of vaterite."

Ferreting out the structure of the mineral, according to Gilbert, a UW-Madison professor of physics, was challenging because of the difficulty of finding large, pure single crystals of vaterite. Enter Herdmania momus, a solitary sea squirt, and member of a large family of filter-feeding marine invertebrates.

"This organism makes the best crystal," avers Gilbert, an expert on crystalline biominerals formed by marine animals. "Geologic vaterite is extremely rare and unstable. The synthetic version is a powder and yields only small crystal grains with poor structure."

In nature, sea squirts and sponges use spicules as a skeleton to provide structural support. The spicule from the sea squirt Herdmania momus is composed of a large, single crystal that Pokroy and Gilbert used to unmask the atomic structure of its constituent biomineral vaterite using state-of-the-art high-resolution transmission electron microscopy at Technion.

"The Herdmania momus spicules were known to be made of vaterite since 1975 when a paper by the late Heinz Lowenstam of CalTech was published in Science," notes Pokroy. "It was clear that this would be the best source of biogenic vaterite and geologic vaterite we could ever find."

The big discovery, say Gilbert and Pokroy, is that vaterite is really two interspersed crystal structures: "It changes the concept of vaterite," Pokroy says, explaining that knowledge of the atomic properties of a crystalline structure enable prediction and explanation of its physical properties. "Now we know that 'vaterite' is not just one structure, but is composed of two different ones."

"The second crystal structure in vaterite is less abundant," says Gilbert, "occurring only at the nano scale, and is visible only in certain orientations, and its atomic structure remains unknown."

.


Related Links
University of Wisconsin-Madison
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





TECH SPACE
NASA, Partners Solicit Creative Materials Manufacturing Solutions
Washington DC (SPX) Apr 29, 2013
NASA, the U.S. Agency for International Development (USAID), the U.S. State Department and Nike have issued a challenge to identify 10 game-changing innovations that could enable fabric systems to enhance global economic growth, drive human prosperity and replenish the planet's resources. The challenge is open through July 15 and seeks creative innovations in the materials from which fabri ... read more


TECH SPACE
Vaterite: Crystal within a crystal helps resolve an old puzzle

Space debris problem now urgent - scientists

Nothing Bugs These NASA Aeronautical Researchers

US eases export rules on aerospace parts

TECH SPACE
Gilat to Equip IDF with SatTrooper-1000 Military Manpack

General Dynamics' WIN-T Increment 2, Soldiers' "On-the-Move" Network, Advances as 10th Mountain Division Trains for Deployment

Lockheed Martin Awarded Contract to Modernize U.S. Joint Theater Air Operations System

Boeing Delivers FAB-T Test Units to US Air Force

TECH SPACE
On the record with... Stephane Israel, Arianespace Chairman and CEO

Vega's three-satellite payload is integrated and ready for launch

NASA Seeks Innovative Suborbital Flight Technology Proposals

Stephane Israel named Chairman and CEO of Arianespace

TECH SPACE
Russia launches latest satellite in its global positioning system

Sat-nav warns London lorry drivers of cyclists

TomTom says sales fall, turning from navigation market

Northrop Grumman's Astro Aerospace Receives Follow-On Order for 48 More JIB Antennas for GPS III Satellites

TECH SPACE
Australia unveils its F-35 JSF 'Iron Bird'

China welcomes French president with Airbus deal

Multifunction Advanced Data Link Flight Tested For F-35 Program

Brazil drops plan to build AgustaWestland helicopter

TECH SPACE
New Research Findings Open Door to Zinc-Oxide-based UV Lasers, LED Devices

New Nanowire Structure Has Potential to Increase Semiconductor Applications

Scientists provide 'new spin' on emerging quantum technologies

Germanium made compatible

TECH SPACE
NASA's HyspIRI: Seeing the Forest and the Trees and More

Satrec Initiative of South Korea Continues Collaboration with UAE for DubaiSat-3 Program

Google says Street View data now take in 50 countries

DMCii increases downlink capacity with Svalbard ground station facilities

TECH SPACE
Researchers pinpoint how trees play role in smog production

Research Harnesses Solar-Powered Proteins to Filter Harmful Antibiotics from Water

European lawmakers tighten rules on ship-breaking industry

Albania to hold referendum on waste imports




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement