Tag Archives: chemistry

The DC-8 airborne laboratory is one of several NASA aircraft that will fly in support of five new investigations into how different aspects of the interconnected Earth system influence climate change.
Image Credit: NASA

NASA Airborne Campaigns Tackle Climate Questions from Africa to Arctic

Five new NASA airborne field campaigns will take to the skies starting in 2015 to investigate how long-range air pollution, warming ocean waters, and fires in Africa affect our climate.

These studies into several incompletely understood Earth system processes were competitively-selected as part of NASA’s Earth Venture-class projects. Each project is funded at a total cost of no more than $30 million over five years. This funding includes initial development, field campaigns and analysis of data.

This is NASA’s second series of Earth Venture suborbital investigations — regularly solicited, quick-turnaround projects recommended by the National Research Council in 2007. The first series of five projects was selected in 2010.

“These new investigations address a variety of key scientific questions critical to advancing our understanding of how Earth works,” said Jack Kaye, associate director for research in NASA’s Earth Science Division in Washington. “These innovative airborne experiments will let us probe inside processes and locations in unprecedented detail that complements what we can do with our fleet of Earth-observing satellites.”

The DC-8 airborne laboratory is one of several NASA aircraft that will fly in support of five new investigations into how different aspects of the interconnected Earth system influence climate change. Image Credit: NASA
The DC-8 airborne laboratory is one of several NASA aircraft that will fly in support of five new investigations into how different aspects of the interconnected Earth system influence climate change.
Image Credit: NASA

The five selected Earth Venture investigations are:

  • Atmospheric chemistry and air pollution – Steven Wofsy of Harvard University in Cambridge, Massachusetts, will lead the Atmospheric Tomography project to study the impact of human-produced air pollution on certain greenhouse gases. Airborne instruments will look at how atmospheric chemistry is transformed by various air pollutants and at the impact on methane and ozone which affect climate. Flights aboard NASA’s DC-8 will originate from the Armstrong Flight Research Center in Palmdale, California, fly north to the western Arctic, south to the South Pacific, east to the Atlantic, north to Greenland, and return to California across central North America.
  • Ecosystem changes in a warming ocean – Michael Behrenfeld of Oregon State University in Corvallis, Oregon, will lead the North Atlantic Aerosols and Marine Ecosystems Study, which seeks to improve predictions of how ocean ecosystems would change with ocean warming. The mission will study the annual life cycle of phytoplankton and the impact small airborne particles derived from marine organisms have on climate in the North Atlantic. The large annual phytoplankton bloom in this region may influence the Earth’s energy budget. Research flights by NASA’s C-130 aircraft from Wallops Flight Facility, Virginia, will be coordinated with a University-National Oceanographic Laboratory System (UNOLS) research vessel. UNOLS, located at the University of Rhode Island’s Graduate School of Oceanography in Narragansett, Rhode Island, is an organization of 62 academic institutions and national laboratories involved in oceanographic research.
  • Greenhouse gas sources – Kenneth Davis of Pennsylvania State University in University Park, will lead the Atmospheric Carbon and Transport-America project to quantify the sources of regional carbon dioxide, methane and other gases, and document how weather systems transport these gases in the atmosphere. The research goal is to improve identification and predictions of carbon dioxide and methane sources and sinks using spaceborne, airborne and ground-based data over the eastern United States. Research flights will use NASA’s C-130 from Wallops and the UC-12 from Langley Research Center in Hampton, Virginia.
  • African fires and Atlantic clouds – Jens Redemann of NASA’s Ames Research Center in Mountain View, California, will lead the Observations of Aerosols above Clouds and their Interactions project to probe how smoke particles from massive biomass burning in Africa influences cloud cover over the Atlantic. Particles from this seasonal burning that are lofted into the mid-troposphere and transported westward over the southeast Atlantic interact with permanent stratocumulus “climate radiators,” which are critical to the regional and global climate system. NASA aircraft, including a Wallops P-3 and an Armstrong ER-2, will be used to conduct the investigation flying out of Walvis Bay, Namibia.
  • Melting Greenland glaciers – Josh Willis of NASA’s Jet Propulsion Laboratory in Pasadena, California, will lead the Oceans Melting Greenland mission to investigate the role of warmer saltier Atlantic subsurface waters in Greenland glacier melting. The study will help pave the way for improved estimates of future sea level rise by observing changes in glacier melting where ice contacts seawater. Measurements of the ocean bottom as well as seawater properties around Greenland will be taken from ships and the air using several aircraft including a NASA S-3 from Glenn Research Center in Cleveland, Ohio, and Gulfstream III from Armstrong.

Seven NASA centers, 25 educational institutions, three U.S. government agencies and two industry partners are involved in these Earth Venture projects. The five investigations were selected from 33 proposals.

Earth Venture investigations are part of NASA’s Earth System Science Pathfinder program managed at Langley for NASA’s Science Mission Directorate in Washington. The missions in this program provide an innovative approach to address Earth science research with periodic windows of opportunity to accommodate new scientific priorities.

NASA monitors Earth’s vital signs from land, sea, air and space with a fleet of satellites and ambitious airborne and surface-based observation campaigns. With this information and computer analysis tools, NASA studies Earth’s interconnected systems to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

For more information about NASA’s Earth science activities, visit:

http://www.nasa.gov/earthrightnow

Source: NASA

In a paper appearing in the Nov. 18 issue of Nature Communications, the researchers demonstrate the use of the particles, which carry distinct sensors for fluorescence and MRI, to track vitamin C in mice. Wherever there is a high concentration of vitamin C, the particles show a strong fluorescent signal but little MRI contrast. If there is not much vitamin C, a stronger MRI signal is visible but fluorescence is very weak.

Illustration: Christine Daniloff/MIT

Two sensors in one

Nanoparticles that enable both MRI and fluorescent imaging could monitor cancer, other diseases.

By Anne Trafton


 

MIT chemists have developed new nanoparticles that can simultaneously perform magnetic resonance imaging (MRI) and fluorescent imaging in living animals. Such particles could help scientists to track specific molecules produced in the body, monitor a tumor’s environment, or determine whether drugs have successfully reached their targets.

 

In a paper appearing in the Nov. 18 issue of Nature Communications, the researchers demonstrate the use of the particles, which carry distinct sensors for fluorescence and MRI, to track vitamin C in mice. Wherever there is a high concentration of vitamin C, the particles show a strong fluorescent signal but little MRI contrast. If there is not much vitamin C, a stronger MRI signal is visible but fluorescence is very weak.

In a paper appearing in the Nov. 18 issue of Nature Communications, the researchers demonstrate the use of the particles, which carry distinct sensors for fluorescence and MRI, to track vitamin C in mice. Wherever there is a high concentration of vitamin C, the particles show a strong fluorescent signal but little MRI contrast. If there is not much vitamin C, a stronger MRI signal is visible but fluorescence is very weak. Illustration: Christine Daniloff/MIT
In a paper appearing in the Nov. 18 issue of Nature Communications, the researchers demonstrate the use of the particles, which carry distinct sensors for fluorescence and MRI, to track vitamin C in mice. Wherever there is a high concentration of vitamin C, the particles show a strong fluorescent signal but little MRI contrast. If there is not much vitamin C, a stronger MRI signal is visible but fluorescence is very weak.
Illustration: Christine Daniloff/MIT

 

Future versions of the particles could be designed to detect reactive oxygen species that often correlate with disease, says Jeremiah Johnson, an assistant professor of chemistry at MIT and senior author of the study. They could also be tailored to detect more than one molecule at a time.

 

“You may be able to learn more about how diseases progress if you have imaging probes that can sense specific biomolecules,” Johnson says.

 

Dual action

 

Johnson and his colleagues designed the particles so they can be assembled from building blocks made of polymer chains carrying either an organic MRI contrast agent called a nitroxide or a fluorescent molecule called Cy5.5.

 

When mixed together in a desired ratio, these building blocks join to form a specific nanosized structure the authors call a branched bottlebrush polymer. For this study, they created particles in which 99 percent of the chains carry nitroxides, and 1 percent carry Cy5.5.

 

Nitroxides are reactive molecules that contain a nitrogen atom bound to an oxygen atom with an unpaired electron. Nitroxides suppress Cy5.5’s fluorescence, but when the nitroxides encounter a molecule such as vitamin C from which they can grab electrons, they become inactive and Cy5.5 fluoresces.

 

Nitroxides typically have a very short half-life in living systems, but University of Nebraska chemistry professor Andrzej Rajca, who is also an author of the new Nature Communications paper, recently discovered that their half-life can be extended by attaching two bulky structures to them.  Furthermore, the authors of the Nature Communications paper show that incorporation of Rajca’s nitroxide in Johnson’s branched bottlebrush polymer architectures leads to even greater improvements in the nitroxide lifetime. With these modifications, nitroxides can circulate for several hours in a mouse’s bloodstream — long enough to obtain useful MRI images.

 

The researchers found that their imaging particles accumulated in the liver, as nanoparticles usually do. The mouse liver produces vitamin C, so once the particles reached the liver, they grabbed electrons from vitamin C, turning off the MRI signal and boosting fluorescence. They also found no MRI signal but a small amount of fluorescence in the brain, which is a destination for much of the vitamin C produced in the liver. In contrast, in the blood and kidneys, where the concentration of vitamin C is low, the MRI contrast was maximal.

 

Mixing and matching

 

The researchers are now working to enhance the signal differences that they get when the sensor encounters a target molecule such as vitamin C. They have also created nanoparticles carrying the fluorescent agent plus up to three different drugs. This allows them to track whether the nanoparticles are delivered to their targeted locations.

 

“That’s the advantage of our platform — we can mix and match and add almost anything we want,” Johnson says.

 

These particles could also be used to evaluate the level of oxygen radicals in a patient’s tumor, which can reveal valuable information about how aggressive the tumor is.

 

“We think we may be able to reveal information about the tumor environment with these kinds of probes, if we can get them there,” Johnson says. “Someday you might be able to inject this in a patient and obtain real-time biochemical information about disease sites and also healthy tissues, which is not always straightforward.”

 

Steven Bottle, a professor of nanotechnology and molecular science at Queensland University of Technology, says the most impressive element of the study is the combination of two powerful imaging techniques into one nanomaterial.

 

“I believe this should deliver a very powerful, metabolically linked, multi-combination imaging modality which should provide a highly useful diagnostic tool with real potential to follow disease progression in vivo,” says Bottle, who was not involved in the study.

 

The research was funded by the National Institutes of Health, the Department of Defense, the National Science Foundation, and the Koch Institute for Integrative Cancer Research.

Source: MIT News

 

KAUST team synthesizes novel metal-organic framework for efficient CO2 removal

By Caitlin Clark

“In Professor Mohamed Eddaoudi’s research group, we are always on the quest to find novel nanostructured functionalized materialsfor specific applications,” explained KAUST Research Scientist Dr. Youssef Belmabkhout, a member of Prof. Eddaoudi’s Functional Materials Design, Discovery, and Development (FMD3) group, part of KAUST’s Advanced Membranes and Porous Materials (AMPM) research center.

Dr. Osama Shekhah, Senior Research Scientist in the FMD3 group added that the group searches “for materials that will be highly suitable for trace and low CO2 concentration removal using purely physical adsorption. These will help in energy saving and in the reduction of the cost of the production, purification, and enrichment of highly valuable commodities such as CH4, H2, O2, N2, and others.”

Drs. Shekhah and Belmabkhout and a team of researchers from Prof. Eddaoudi’s group recently discovered and synthesized a new porous, moisture-resistant, inexpensive and reusable copper-based metal-organic framework (MOF) called SIFSIX-3-Cu that can selectively adsorb and remove trace CO2 from mixtures of various gases. Their findings were published in the June 25 edition of Nature Communications (DOI: 10.1038/ncomms5228).

MOFs are a promising new class of hybrid solid-state materials for CO2 removal. “Their uniqueness,” explained Prof. Eddaoudi, “resides in the ability to control their assembly and introduce functionality on demand. This feature is not readily available in other solid-state materials.”

The researchers showed for the first time that MOF crystal chemistry permits the assembly of a new isostructural hexafluorosilicate MOF (SIFSIX-3-Cu) based on copper instead of zinc.

“This technology is anticipated to outperform the existing mature technologies for CO2 physical adsorption in terms of energy efficiency,” says Dr. Shekhah. “The key factors for this finding are the combination of suitable pore size and high, uniform charge density in the pores of the MOF.”

Using their newly synthesized MOF, the researchers examined the conditions relevant to direct air capture (DAC), a mechanism to remove CO2 from air and reduce greenhouse gas emissions uniformly around the world.

DAC is more challenging than post-combustion capture, but it may be practical if alternative “suitable adsorbent combining optimum uptake, kinetics, energetics and CO2 selectivity is available at trace CO2 concentration,” the researchers stated.

The team discovered that contracting SIFSIX-3-Cu’s pore system to 3.5 Å enhanced the material’s efficiency, making it able to adsorb relatively large CO2 amounts 10-15 times higher than zinc-based metal-organic adsorbents, such as SIFSIX-3-Zn. In SIFSIX-3-Zn, the pore size is 3.84 Å.

“We attribute this property to enhanced physical sorption through the favorable electrostatic interactions between CO2 molecules and fluorine atoms present on the surface of the adsorbent,” explained Zhijie Chen, a Ph.D. student in the FMD3 group and a co-author of the paper.

Dr. Vincent Guillerm, a post-doctoral fellow in the FMD3 group and a co-author of the paper also noted that, “the pore contraction gives CO2 uptake and selectivity at very low partial pressures. This is relevant to DAC and trace carbon dioxide removal.”

“SIFSIX-3-Cu gives enhanced CO2 physical adsorption properties, uptake, and selectivity in highly diluted gas streams, and this performance is unachievable with other classes of porous materials,” added Dr. Karim Adil, a co-author of the paper and Research Scientist in the FMD3 group.

The researchers are excited about their finding as it offers the potential to be used not only for DAC but also for other applications related to energy, the environment, and the healthcare field. For example, SIFSIX-3-Cu could be used to remove and recycle CO2 in confined spaces, such as in submarines or space shuttles, and could also be used in anesthesia machines, which require efficient CO2 sorbents.

“Our work paves the way for scientists to develop new separation agents suitable for challenging endeavor pertaining to CO2 ultra-purification processing,” said Dr. Shekhah. “Our study is also part of a greater critical effort to develop economical and practical pathways to reduce cumulative CO2 emissions provoking the undesirable greenhouse gas effect.”

Prof. Eddaoudi reiterated that “MOFs offer remarkable CO2 physical adsorption attributes in highly diluted gas streams thanks to their ability for rational pore size modification and inorganic-organics moieties substitution. Other classes of plain materials are unable to attain this.”

In the future, Prof. Eddaoudi’s FMD3 group will continue to develop topologically and chemically different MOFs. “We aim to target novel MOFs with suitable pore size and high charge density,” explained Prof. Eddaoudi. “We will then use these for the important task of removing trace and low and high concentration CO2.”

Source: KAUST


 

Nobel Chemistry 2014: “for the development of super-resolved fluorescence microscopy”

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Chemistry for 2014 to

Eric Betzig
Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA,

Stefan W. Hell
Max Planck Institute for Biophysical Chemistry, Göttingen, and German Cancer Research Center, Heidelberg, Germany

and

William E. Moerner
Stanford University, Stanford, CA, USA

“for the development of super-resolved fluorescence microscopy”

Surpassing the limitations of the light microscope

For a long time optical microscopy was held back by a presumed limitation: that it would never obtain a better resolution than half the wavelength of light. Helped by fluorescent molecules the Nobel Laureates in Chemistry 2014 ingeniously circumvented this limitation. Their ground-breaking work has brought optical microscopy into the nanodimension.

In what has become known as nanoscopy, scientists visualize the pathways of individual molecules inside living cells. They can see how molecules create synapses between nerve cells in the brain; they can track proteins involved in Parkinson’s, Alzheimer’s and Huntington’s diseases as they aggregate; they follow individual proteins in fertilized eggs as these divide into embryos.

It was all but obvious that scientists should ever be able to study living cells in the tiniest molecular detail. In 1873, the microscopist Ernst Abbe stipulated a physical limit for the maximum resolution of traditional optical microscopy: it could never become better than 0.2 micrometres. Eric BetzigStefan W. Helland William E. Moerner are awarded the Nobel Prize in Chemistry 2014 for having bypassed this limit. Due to their achievements the optical microscope can now peer into the nanoworld.

Two separate principles are rewarded. One enables the method stimulated emission depletion (STED) microscopy, developed by Stefan Hell in 2000. Two laser beams are utilized; one stimulates fluorescent molecules to glow, another cancels out all fluorescence except for that in a nanometre-sized volume. Scanning over the sample, nanometre for nanometre, yields an image with a resolution better than Abbe’s stipulated limit.

Eric Betzig and William Moerner, working separately, laid the foundation for the second method, single-molecule microscopy. The method relies upon the possibility to turn the fluorescence of individual molecules on and off. Scientists image the same area multiple times, letting just a few interspersed molecules glow each time. Superimposing these images yields a dense super-image resolved at the nanolevel. In 2006 Eric Betzig utilized this method for the first time.

Today, nanoscopy is used world-wide and new knowledge of greatest benefit to mankind is produced on a daily basis.

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Eric Betzig, U.S. citizen. Born 1960 in Ann Arbor, MI, USA. Ph.D. 1988 from Cornell University, Ithaca, NY, USA. Group Leader at Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
http://janelia.org/lab/betzig-lab

Stefan W. Hell, German citizen. Born 1962 in Arad, Romania. Ph.D. 1990 from the University of Heidelberg, Germany. Director at the Max Planck Institute for Biophysical Chemistry, Göttingen, and Division head at the German Cancer Research Center, Heidelberg, Germany.
http://www3.mpibpc.mpg.de/groups/hell

William E. Moerner, U.S. citizen. Born 1953 in Pleasanton, CA, USA. Ph.D. 1982 from Cornell University, Ithaca, NY, USA. Harry S. Mosher Professor in Chemistry and Professor, by courtesy, of Applied Physics at Stanford University, Stanford, CA, USA.
http://web.stanford.edu/group/moerner

The Prize amount: SEK 8 million, to be shared equally between the Laureates.

Source: NobelPrize.Org