Research Rundown

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Science Journal, Spring 1999 -- Vol 16, No. 1

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Porous "Nanobubblepack" Materials Discovered at Penn State

A new class of porous materials with an orderly crystal-like arrangement of ultra-small spherical spaces has been discovered by chemists at Penn State.  A paper describing the "nanobubblepack" discovery was published in the February 12, 1999, issue of the journal Science.  The researchers report that they can produce the material in a range of pore sizes never before achieved, opening the door to a variety of potential uses in industry and research.

"It looks like we can easily make lots of this porous material out of anything, and we also can fill it up with anything," says Thomas Mallouk, professor of chemistry at Penn State and principal author of the paper describing the research.  "It is intriguing to think about all the ways it might be used."

Mallouk says two of his graduate students, Stacy A. Johnson and Patricia J. Ollivier, initially proposed the idea for making the material.  "Stacy and Patti were trying to do two things nobody had done before: make organic porous materials using uniform inorganic materials as a template, and make uniform pores in the size range between 10 and 100 nanometers," Mallouk says.

Other researchers had been able to make uniform pores using a fabrication process developed by Penn State materials scientists in the 1970s.  They could make either pores larger than 100 nanometers, using polymer spheres as templates, or they could make pores smaller than 10 nanometers, using small molecules or groups of molecules as templates, but they could not make pores between 10 and 100 nanometers because there were no suitable templates in that size range--bigger than a molecule but smaller than a cell.

Johnson and Ollivier told Mallouk they had read a 1990 paper by Kwadwo A. Osseo-Asare, a professor of metallurgy at Penn State, in which he described how to make identical spheres of silica, an inorganic material, only 35 nanometers in diameter.  The students wanted to try using Osseo-Asare's high-tech sand as a template for making an organic material with 35-nanometer pores--well within the size range not yet achieved by other researchers.

Under Mallouk's direction, the students first filled a pellet press with the 35-nanometer silica spheres, then pressed and heated them to form a colloidal-crystal pellet in which all the silica spheres were closely packed in an orderly arrangement.  The researchers then used this pellet as a mold, saturating the spaces between the spheres with a liquid monomer--the chemical precursor of a polymer.  They next processed the pellet to transform the liquid monomer into a solid polymer and chemically dissolved the silica spheres.  "What you get is 75 percent empty space made up of identical spherical chambers surrounded by an organic polymer--the same shape and orderly arrangement as the silica spheres you started with," Mallouk says.  "It's something like nanobubblepack--except that the chambers are connected by channels, which makes this material particularly porous."

Johnson and Ollivier next tried making the material with different mixtures of one monomer that has a tendency to shrink (EDMA) and another monomer that does not (DVB).  "When you use EDMA alone, it shrinks by a factor of about 2.5 as soon as you etch the silica spheres away, so if you start with 35-nanometer spheres you know you're going to get 15-nanometer pores," Mallouk explains.  "We can get a range of uniform pore sizes, anywhere between 15 and 35 nanometers, just by varying the mixture of EDMA and DVB--it's like having a reducing photocopy machine for porous materials," Mallouk says.

The researchers say they can dial in a specific pore size anywhere they want in the previously untouched size range.  "Lots of people use the replication process to make materials, but it had not been used in this size range before and no one had ever made an organic replica of an inorganic material on anywhere near this length scale," Mallouk adds.  "Unlike many other precision materials that are difficult to fabricate, you easily can make pounds of this very-well-behaved stuff," Mallouk says.

Other researchers in Mallouk's lab are now exploring methods for tailoring the chemistry of the pores for specific applications and are using the shrunken porous material to make miniature replicas of the initial silica spheres.  "We are trying to use these materials to separate chiral molecules, which are chemically identical but come in left-handed and right-handed forms," Mallouk explains.  The separation of chiral molecules is an important process in the pharmaceutical industry.  "The goal is to tailor the chemistry of the pores so they will capture only the left or right form as a mixed stream of molecules flows through the material," he adds.

"There are all sorts of interesting potential uses, both in basic research and in industry, for ordered porous materials in this size range," Mallouk says.

One potential for basic research involves fundamental questions about how the physics of a material changes as it is cut into smaller and smaller pieces.  "Magnetism, ferroelectricity in semiconductors, and certain optical properties disappear in a material if you break it into small enough pieces," Mallouk explains.  Particles made in precise sizes in the pores of his new material could be useful to researchers trying to understand how the fundamental physics of such properties changes with decreasing size and to learn exactly when molecular-scale properties start to take over.  Mallouk says intriguing uses also are possible in biological research because the smallest compartments he and his students made are about the right size for holding an individual enzyme molecule.  "You might be able to make more stable and longer-lasting sensors or chemical reactors, like the glucose sensors used by diabetics, if you could use the pores as enzyme cages for controlling each enzyme's reaction environment," Mallouk speculates.

Other potential technological applications include using the pores as isolation chambers with the low dielectric conditions needed for preventing microelectronic circuit components from interfering with each other.  "The lowest dielectric constant you can get is that of empty space, and these materials are 75 percent empty space," Mallouk comments.

"We also think that, because the length scale of these pores is well below the wavelength of light, any material we could make with them would be transparent--even a metal--because it would not be able to scatter light," Mallouk says.  "It is exciting to have control over both the composition and the length scale of this new material because that gives us the tools for exploring lots of different possibilities."

Stacy A. Johnson and Patricia J. Ollivier have completed their graduate studies and are now employed by DuPont at its research facilities in Virginia and North Carolina.  Mallouk has filed a patent application for the discovery.  This research was supported by the National Institutes of Health.

Turtles, not birds, have been found to be the closest relatives of crocodiles and alligators, according to an analysis of the largest available collection of reptile genes.  The study's conclusions contradict decades of research based on anatomical and fossil studies, which had firmly positioned birds as the reptile group most closely related to crocodiles and alligators, a group known as crocodilians.

The surprising finding was published in the February 12, 1999, issue of the journal Science by researchers S. Blair Hedges, an associate professor of biology at Penn State, and Laura L. Poling, a graduate student.

Previous studies of gene similarities--a relatively newer tool for determining relationships between species--have never agreed with the more traditional anatomical methods on this issue.  "Turtles turned out to be not where they were supposed to be on the family tree whenever their genes were included in a research study," says Hedges, who decided recently to assemble all the genetic data available in order to resolve the question.

Hedges and Poling collected new data for two nuclear genes and added this new information to all gene-sequence data available for these species in the public genetic databases worldwide.  The research included 24 genes from the nucleus and 9 DNA segments from the mitochondria of reptile cells.  "The results provide strong evidence that the turtle is the crocodile's closest living relative," Hedges concludes.

Because the ultimate goal of both anatomical studies and gene studies is to find the proper place of all species on the family tree, researchers would like to see agreement between the two types of studies, wherever possible.  To encourage their anatomist colleagues, Hedges and Poling point to an extinct species from the Triassic era, the aetosaur, which appears to share some anatomical characteristics of both turtles and crocodilians.  "We hope paleontologists will take a closer look at reptile fossils from this period to see if they can find any patterns of physical characteristics that would logically reposition the turtle on the family tree in a way consistent with the results of our large study of its genes."

This research was supported, in part, by grants from the National Science Foundation, the National Aeronautics and Space Administration, and a Howard Hughes Medical Institute grant through the Undergraduate Biological Sciences Education Program to Pennsylvania State University.

Early results from the largest new survey of dying stars in the Virgo Cluster reveal the existence of large numbers of stars in areas of space that previously appeared to be empty.  The discovery, which uses dying stars known as planetary nebulae as tools for probing the universe, indicates that at least 22 percent of Virgo's light is coming from previously unknown stars that populate the space between the cluster's galaxies.

The discovery was made by John J. Feldmeier, a Penn State graduate student, Robin Ciardullo, associate professor of astronomy and astrophysics at Penn State, and George H. Jacoby, staff astronomer at Kitt Peak National Observatories, using observations from the National Science Foundation's (NSF) Kitt Peak National Observatory in Tucson, Arizona.  The astronomers presented their discovery during the 193rd National Meeting of the American Astronomical Society.

"Planetary nebulae are dying stars having what I call a stellar heart attack--a very short phase that most stars will go through at the end of their lifetime," Feldmeier explains.  When a star is in the planetary nebula phase, its outside layers of gas come off, exposing its very hot inner core, which ionizes and lights up the gas around it in only a few specific wavelengths.  "A huge amount of green light comes out at the 5007-angstrom wavelength, but not, for example, at 5006 angstroms or 5008 angstroms," Feldmeier says.

The astronomers used a technique, which Ciardullo and Jacoby developed, that takes advantage of this strange green starlight.  "We take a picture through a filter that accepts only 5007 angstroms, and another picture through a filter that accepts only a different wavelength, and when we subtract the two all the planetary nebulae just pop right out as distinct points of light," Feldmeier explains.

The astronomers have used their technique to discover 130 previously unknown planetary nebulae in six small patches during the initial phase of their large-scale survey of the space between galaxies in the Virgo Cluster.  "We are able to see the planetary nebulae even though they are literally 48 million light years away," Feldmeier explains.  "We expect to find tens of thousands of planetary nebulae as we piece together a more complete picture of the Virgo Cluster, and to use them to know Virgo better than any other galaxy cluster in the universe," Ciardullo adds.

Feldmeier, Ciardullo, and Jacoby are using the green glow of the planetary nebulae as beacons to shine light on a number of astronomical mysteries, including how much mass might be hiding between galaxies throughout the universe, how galaxies form and change in a cluster, how long ago the Virgo Cluster formed, the three-dimensional shape of the Virgo Cluster, and where the orphan stars were born.

"For every planetary nebula we see during its short stellar-heart-attack phase, there are literally millions of other normal stars in other phases of their life that we can't see out there," Ciardullo says, "so we think the stellar mass of this cluster has been underestimated."  The researchers say their findings could affect estimates of the amount of mass the universe contains, which is a critical element in attempts to model the evolution and eventual fate of the universe.  "Our research indicates that at least some of the 'missing mass' needed for some models is not some form of exotic matter but just normal stars that we could not detect before, which could affect existing models of how the universe works," Ciardullo comments.

The astronomers say their evidence also tentatively supports the idea that one way galaxies change in clusters is by disrupting each other during grazing near-miss encounters.  The idea is that when galaxies in a crowded cluster careen past each other, some of their stars can be tugged so strongly by the gravity of the passing mass that they get ripped out of the parent galaxy, leaving an arching trail of stars hanging in space.  "Basically, it's like demolition derby," Feldmeier explains.  "The longer the galaxies have had to run into each other the more beaten up they get and the more they make what I call orphan stars," Feldmeier says.

"We think we will be able to tell something about the age and energy of a galaxy cluster by using planetary nebulae to gauge the distribution and number of the intergalactic orphan stars it contains," Ciardullo adds.  Well-formed trails of green-glowing stars would indicate a cluster of moderate age--old enough to have had interactions between its galaxies but not so old as to have destroyed the evidence.  "We are just starting to piece together a larger patchwork picture of Virgo, and one of our first results is that these planetary nebulae are not randomly distributed but appear to be clustered in some way that could possibly be these arching trails," Ciardullo says.  "Eventually, when we have a more complete picture of the cluster, we hope to be able to see these trails of green stars and, perhaps, follow the trail from one galaxy to the other finding intracluster stars along the whole way," Feldmeier adds.

Another clue the astronomers discovered is that the planetary nebulae contain oxygen, which can be created only deep in the cores of a previous generation of stars that have exploded into space at the end of their lifetime and then been compressed again by gravity into their present form.  The researchers reason that, because the intracluster stars formed from the recycled stardust of a previous generation of stars, they are more likely to have formed where there are lots of other stars--in a galaxy--than alone in an isolated area of space.  "It is rather remarkable, I think, that we can now say it looks like these stars have been ripped out of galaxies in the not-so-distant past," Ciardullo remarks.  "As we gather more data during this survey, we hope to be able to tighten up that argument."

The researchers also learned something about the three-dimensional shape of the Virgo Cluster by using another unusual characteristic of planetary nebulae, which is that there is a maximum limit to how bright they can get.  "We were able to map the area around the galaxy named M87, which people generally accept as Virgo's core, and we found that Virgo is shaped more like a football than a sphere--it's longer pointing toward us than side to side," Ciardullo says.  Because the astronomers make the assumption that all the planetary nebulae in the Virgo cluster attain the same maximum possible brightness, they can use the stars' apparent brightness when observed from Earth to judge their relative distances--those that appear to be dimmer are assumed to be farther away from Earth.  "If it actually is fainter than you assume, it could be even closer but not farther away," Ciardullo explains.

This spring, the team plans to use a much larger camera at the Kitt Peak observatory, which will allow them to survey five times as much area in the same amount of time.  "Instead of finding 130, we could find 600," Feldmeier speculates.  "We are probing this cluster in a way that no one has done before--by using planetary nebulae to look between the galaxies at the stars that have been orphaned--and are discovering things that we could not have learned another way," Ciardullo says.

This research was supported, in part, by the National Aeronautical and Space Administration and the National Science Foundation.  The Kitt Peak National Observatory is one of four divisions of the National Optical Astronomy Observatories (NOAO).  NOAO is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.

A series of discoveries that dramatically alter the understanding of how cells turn genes on were announced in recent issues of the international science journals Nature and Cell.  The research, which reviewers at Cell have described as "provocative and highly significant," reveals molecules previously unknown to be involved in gene expression plus unexpected dynamics among these molecules, which work together as a team to activate genes.

"Gene-activation is a factor in diseases involving cancers, viruses, and hormones, and we now are starting to get a much more detailed understanding of how this important process works," says Jerry L. Workman, associate professor of molecular and cell biology at Penn State and the leader of the research group that made the discoveries.

Workman's research reveals new players on the team of molecules that turns on a gene--a precise section of DNA containing one of the cell's operating instructions--by making a copy of its code, which the cell then uses as a template for making whatever protein the gene is designed to produce.  "Each cell turns on only the particular genes it needs for whatever function it needs to perform," Workman explains.

Scientists already knew some of the players on the gene-copying team, which Workman's research has now shown to be much larger and more complicated.  They knew that inactive genes are locked inside densely knotted structures called nucleosomes.  They also knew that the nucleosome knots are held together by powerful histone proteins, whose grip has to be broken before a gene can loosen up enough to be turned on by another kind of molecule, the transcription enzyme RNA polymerase.  "RNA polymerase turns a gene on by attaching to it and moving along its length, making an RNA copy of its DNA code," Workman explains.  Recently Workman's lab also characterized a powerful enzyme called SWI/SNF that overpowers the histone proteins, untangling the gene and making it accessible to the RNA polymerase enzyme.  Plus, they showed recently that another molecule, a transcription activator, helps RNA polymerase attach exactly at the right spot on the DNA to start copying a specific gene.

Now, Workman's lab has identified even more molecular players plus the roles they play and some of the complex interactions among them.  "Rhea Utley, a graduate student in our group, discovered that the transcription activators directly link to a very large protein group called a histone acetyltransferase complex (HAT), which contains an enzyme called Gcn5 that remodels nucleosomes by attaching a chemical group called an acetate," Workman says.  "Dave Steger, a postdoc in the group, found that this acetylation reaction is involved very intimately in the regulation of gene transcription," explains Workman, who speculates that it somehow helps the RNA polymerase enzyme to copy the gene.

Workman's group also discovered two large HAT complexes containing between ten and twenty proteins each, which they describe in the Cell and Nature papers.  "Once an activator is able to bind to a gene, it can grab one of these HAT complexes and bring it to the gene so that the Gcn5 enzyme can unlock the nucleosomes by adding acetate groups onto the histones," Workman explains.

"Patrick Grant, a postdoc in our group, found that HAT complexes not only contain histone acetylation enzymes but also TAF proteins, which are known to bind to another very large system of proteins known as TFIID, which is important for telling the RNA polymerase where to start copying a gene," Workman says.  "We've also shown that this binding process requires a molecule called Acetyl CoA, which is a little protein that has an acetate group attached to it," he says, explaining that the Gcn5 enzyme takes the acetate group off the Acetyl CoA molecule and adds it to the histones.

One reason the Workman group was able to make so many discoveries at once is that it is the first lab to isolate and purify the individual HAT complexes, and then the individual proteins within each complex, and to make enough of the purified proteins to do experiments designed to find out how each one works.  The purifications were done by current and former postdocs in the Workman lab, including Patrick Grant, Jacques Cote, Anton Eberharter, and Sam John.  "Some of the experiments we've done show that transcription activators and HAT complexes bind to each other," Workman explains.  Some of his other experiments showed that this binding causes the HAT complexes to acetylate only those nucleosomes that are bound by the transcription activator.

"This research changes and complicates quite a bit our picture of how gene regulation at the level of transcription actually is orchestrated," Workman comments.  "It demonstrates that the process controlling gene expression is very dynamic, very interactive, and very complicated."

Supporters of this research include the Howard Hughes Medical Institute, United States National Institutes of Health, National Center for Research Resources, National Institute of General Medical Sciences, American Cancer Society, National Science Foundation Science and Technology Center, Leukemia Society, Austrian Science Foundation, Cancer Research Institute, and Canadian Medical Research Council.  In addition to Workman, researchers at Penn State include Assistant Professor Joseph C. Reese; graduate student Rhea T. Utley, postdoctoral fellows Anton Eberharter, Patrick A. Grant, Keiko Ikeda, Sam John, and David J. Steger; and research associate Marilyn G. Pray-Grant.  Researchers at the University of Washington include research associate David Schieltz and professor John R. Yates, III, and at Laval University include professor Jacques Cote.  Workman is a former Leukemia Society Scholar and is currently a Howard Hughes Medical Institute associate investigator.
 

Astronomers are announcing today that they have discovered expanding gas clouds thrown off by nuclear eruptions in stars. The report was presented by Penn State astronomers Fred Ringwald, Jerome A. Orosz, Richard A. Wade, and Robin B. Ciardullo at a recent American Astronomical Society meeting in San Diego, California. The result is of interest because it provides reliable distances to these stars.

Pictures of the expanding gas clouds, which were taken with the Hubble Space Telescope, are available for viewing on the World Wide Web at http://www.astro.psu.edu/users/ringwald/.  They are among the most detailed pictures of nova shells ever taken, thanks to Hubble's high resolution.

These images, taken with Hubble's refurbished Wide-Field/Planetary Camera, are of two novae stars that had nuclear eruptions in 1984 and 1991. The stars' names are QU Vulpeculae, in the constellation Vulpecula (the Fox with a Duck), and V351 Puppis, in the constellation Puppis (the Afterdeck of Argo, the Ship).  The rings around the stars are expanding clouds of gas thrown off by the eruptions.  The stars in which the eruptions occurred are still visible in the centers of both expanding clouds, called nova shells.

Both images were taken in the red light of hydrogen alpha, where nova shells are known to glow brightly. Until now, nova shells have been hard to study because they are faint and appear to be very small because they are far from Earth.  These two nova shells, for example, are so far away that they appear to be tiny--barely one second of arc in apparent diameter, which is the angle covered by a dime when viewed from over two miles away.

Since it is known how fast the shells are expanding and when the novae erupted, nova shells are useful milestones for calculating distances in space, which are ordinarily difficult to measure.  Ringwald's team found that QU Vul is 18,300 light-years away, and V351 Pup is 14,800 light-years away.

"We know that the shell of QU Vul is expanding at over 2000 miles per second and the shell of V351 Pup is expanding at 3200 miles per second from analyses of the light, previously published in the scientific literature, by Massimo Della Valle at the University of Padova in Italy; George Sonneborn at NASA/Goddard Space Flight Center in Greenbelt, Maryland; and Steve Shore at Indiana University at South Bend, and their collaborators," Ringwald explains.  "The mass of the gas in nova shells is thought to be on the order of 30 times the mass of Earth and the true diameter of both of these shells is about half a trillion miles," he says.

During the nova eruptions, both QU Vul and V351 Pup were just visible to the unaided eye, at fifth and sixth magnitudes, respectively.  They have since faded greatly: V351 Pup is about one million times fainter than the eye can see, and QU Vul is only about six times brighter than that.

"Interestingly, structure is apparent in the nova shells, including what may be polar blobs in the shell of QU Vul, which is known to be edge-on," Ringwald says.  Just visible also are "equatorial" and "temperate" rings. "There is a definite asymmetry in the shell of V351 Pup, perhaps also with polar blobs, approximately perpendicular to those shown in the figure of QU Vul.  This structure is thought to be formed in, or shortly after, the eruptions themselves, although exactly how is still an unsolved problem," Ringwald comments.

The researchers say the Hubble image of QU Vul supports the idea that this structure is formed early, since its polar blobs match the orientation of those seen with a radio telescope shortly after the eruption, when the gas was much hotter than it is now.  A radio map of the shell of QU Vul was published by A. R. Taylor and collaborators in a recent issue of the journal  Nature; the observations were carried out with the Very Large Array radio telescope in New Mexico.

"Nova shells provide unique laboratories for gas dynamics in space, since they change over just a few years, not millennia as with other astronomical gas clouds," Ringwald says.  "By studying nova shells, we can see the wonders of the universe unfold before our very eyes."

This work was supported by Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Aeronautics and Space Administration.
 
 

The most distant object ever found by probing the universe with X-rays has been discovered by an international team of astronomers using the X-ray satellite, ROSAT.  The object, a quasar whose 12-billion-year-old radiation has been speeding toward Earth since the universe was in its infancy, was detected with the deepest X-ray exposure ever made, according to a paper published in a recent issue of the Astronomical Journal.

"This quasar is one of the faintest X-ray sources ever detected," says Donald Schneider, associate professor of astronomy and astrophysics at Penn State and an author of the paper describing the discovery.

Quasars, which are the most luminous objects in the universe and are thought to contain the black-hole seeds from which all galaxies formed, are among the most distant objects known.  "A quasar produces about 100 times as much energy as our entire galaxy but its volume typically is less than the size of our solar system," explains Schneider.  Because radiation from quasars takes billions of years to reach the Earth, scientists see distant quasars as they were billions of years ago and use them as probes to study the early history of the universe.

The researchers discovered the distant quasar, christened "RX J105225.9+571905," by pointing ROSAT's High-Resolution Imager (HRI) X-ray camera at a patch of sky for about a million seconds--a very long time by astronomers' standards--in a study known as the ROSAT Deep Survey.  The group, including astronomers from the United States, Germany, and Italy, obtained enough time on the telescope to look deeper into space in X-rays than anyone ever had done before.  "The purpose of this X-ray survey was to determine the nature of faint X-ray sources, says Guenther Hasinger, director of the Astrophysical Institute in Potsdam, Germany.  "It surprised us by revealing one of the most distant objects known."

In addition to Schneider and Hasinger, other astronomers involved with this work are Maarten Schmidt at the California Institute of Technology, Ingo Lehmann at the University of Potsdam, James Gunn at Princeton University, Riccardo Giacconi at the European Southern Observatory, J. Trümper at the Max Plank Institute, and Gianni Zamorani in Bologna.
The enormous energies released by a quasar result from matter tumultuously tumbling into its central black hole during the initial formation of a galaxy, many astronomers believe.  Quasars are observed to be plentiful early in the history of the universe but to be quite rare today.  The black holes still exist, but have had time by now to devour all the matter within their reach.  "There is good evidence that a black hole resides at the center of our Milky Way galaxy, but we do not see a quasar because there is no material currently falling into the black hole," Schneider says.

In order to gauge the distance from Earth to the objects revealed by ROSAT's X-ray observatory, the scientists had to study them with one of the world's largest optical telescopes, the Keck telescope in Hawaii.  "The X-ray satellite reveals that there is an X-ray source in this part of the sky, but it doesn't tell us what it is and it doesn't tell us how far away it is--we determine that from its visible light," said Hasinger.  The most distant objects are speeding away the fastest, so their visible light appears to be more "redshifted," or skewed toward the red end of the spectrum.

"This quasar is so faint in visible light, it is near the limit of what the giant Keck telescope can measure and--because there are large numbers of optical objects at these brightnesses--our X-ray resolution had to be very accurate in order to determine which object our X-ray source matches in the Keck optical image," Hasinger explains.  The German team, led by Hasinger, developed the techniques that made it possible for the astronomers to assign very accurate celestial positions to X-ray sources in the ROSAT survey.  "The HRI now yields positions that are accurate to about 2 arc seconds--less than one-one-thousandth of a degree--whereas before we were getting positions accurate only within 5 to 10 arc-seconds."

The researchers discovered that the new quasar is located at redshift 4.45, which is so far away that we see it as it appeared when the universe was only about nine percent of its current age.  "Most of the other objects in the survey turned out to be galaxies or quasars much closer to Earth, with redshifts less than two," Schneider says.

While a few objects more distant than the new quasar have been discovered, this is the most distant object ever discovered in an X-ray survey, according to the astronomers.  Niel Brandt, assistant professor of astronomy and astrophysics at Penn State, has been investigating the X-ray properties of distant quasars.  "Altogether, there are about 100 high-redshift quasars now known and X-rays have been detected coming from only about 9 of them," Brandt says.  "We suspect the others are producing X-rays that are just too weak to be detected with our current instruments and typical exposure times."

Astronomers may have to wait only until the end of this year to get a next-generation X-ray camera that will produce much sharper images than are possible now.  The "AXAF Charge-coupled device Imaging Spectrometer" (ACIS), which is scheduled for a Space Shuttle launch this fall, is one of the instruments on the world's most powerful X-ray-astronomy observatory, NASA's Chandra X-Ray Observatory (previously named AXAF, the Advanced X-ray Astrophysics Facility).  The Chandra X-Ray Observatory will be the third of NASA's "Great Observatories" to be launched, following the Hubble Space Telescope, which detects ultraviolet, visible, and infrared rays, and the Compton Gamma-Ray Observatory, which detects gamma rays.  "Among the wonders the ACIS camera is designed to see is the early growth of the seeds of quasars in the infant universe," says Gordon Garmire, the Evan Pugh Professor of Astronomy and Astrophysics at Penn State and the principal investigator who conceived and designed the camera.

"This research holds great promise for our future work at Penn State," Schneider comments.  "With Dr. Garmire's ACIS camera and the next generation of large optical telescopes including the new Hobby-Eberly Telescope, in which Penn State is a major partner, we expect to be able to discover, identify, and locate many more very faint X-ray objects," he says.  "We will be quite surprised if a number of them are not much closer to the beginning of time than the quasar found in our current survey."

This research was supported by the National Science Foundation, the National Aeronautics and Space Administration, the German Center for Space Research, and the Italian Space Agency.

Researchers have discovered two pieces of a scientific puzzle in the most widely used process for removing polluting sulfur compounds from crude oil.  The discovery could help chemists tailor the catalytic process, known as hydrodesulfurization, for maximum efficiency and economy, according to Paul S. Weiss, professor of chemistry at Penn State, who conducted the research along with Penn State graduate student James G. Kushmerick.  A paper describing the research was published in a recent issue of Journal of Physical Chemistry B.

The chemists made their discovery with one of the most powerful and stable microscopes in the world--an instrument they designed and built themselves.  "It is so stable that the position we examine drifts no more than one atomic site per day, so we are able to observe individual molecules for days at a time and to measure the electronic structures that control chemical reactions on surfaces," says Weiss.

The chemists observed a cluster of three nickel atoms and its interaction with a molybdenum disulfide surface.  Tiny molybdenum disulfide crystallites on an oxide base--with nickel or cobalt added as a reaction promoter--are used by
refineries worldwide as catalysts for removing sulfur-containing thiophene compounds from crude oil.

"We were amazed to discover how mobile the nickel atoms were even well below room temperature," says Kushmerick, who had to cool his specimen down to just 4K (degrees Kelvin) above absolute zero and keep it sealed inside his microscope's vacuum chambers to keep the nickel atoms from skimming around the surface in a blur.  "Because the bonds of the molybdenum disulfide are already saturated, there is nothing really to hold the nickel firmly in place," Weiss explains.  The chemists found that, at 4K, the nickel atoms were so loosely bound they were easy to move around with the fine tip of their microscope's needle.

Before this research, it was known that nickel somehow made molybdenum disulfide more effective at bonding with the sulfur in thiophenes, and researchers believed that these reactions could occur only on the edges of the thin catalytic sheets but not on their broad, flat planes.  "Experiments had shown that catalysis was enhanced if the molybdenum disulfide sheets were spread out rather than stacked on top of one another when they were exposed to incoming thiophenes," Weiss explains.  Whether the sheets were spread out or stacked did not affect how much reactive edge area was exposed to the thiophenes, but it greatly affected how much of the unreactive plane area was exposed.  "It was a mystery why the planes would be important when the reactants do not even stick to them," Weiss says, but we think we may have answered part of that question."

Kushmerick and Weiss suspect that nickel's surprising ability to glide around on molybdenum disulfide is one of the keys to how it promotes a more effective catalytic reaction.  "After we got the nickel atoms to stay still on the molybdenum disulfide surface we were able to measure their electronic properties, and we found the cluster's empty electron orbitals were greatly enhanced," Weiss says.  "Occupancy of electron orbitals at specific energies is the major factor that dominates interactions among molecules."

"The nickel cluster had created an excellent place for sulfur in thiophenes to bind because sulfur is nucleophilic--it likes to donate its electrons to empty orbitals," Weiss says.  When the chemists paired this new finding with their discovery of nickel's propensity for skating around on the surface, they realized the nickel atoms could act as a kind of sticky ballbearing--it could both capture thiophenes from the oil and help them move around to find edge sites, where catalytic reactions can lock them in place so they can be separated and chemically removed from the oil.  "If you have reactive nickel atoms roaming around, they are more likely to capture the thiophenes, which would not otherwise stick to the basal plane of the catalytic crystallites," Weiss says.

"We can now think about designing better catalysts by finding promoters that would be most effective at capturing the reactants and allowing them to move around the surface to the best catalytic binding sites," Weiss says.  This discovery also gives chemists a new way to think about how to set up catalytic reactions, in general, by designing systems to enhance surface mobility for reacting molecules.  "Every little bit of efficiency you can get out of these catalytic processes translates into a big effect in terms of results."

This research project received financial support from the National Science Foundation, the Office of Naval Research, the Petroleum Research Fund administered by the American Chemical Society, the Exxon Education Foundation, and Air Products and Chemicals, Inc.  Paul Weiss receives support as a Fellow of the Alfred P. Sloan Foundation and the John Simon Guggenheim Memorial Foundation.

The discovery of the most distant quasar ever observed was announced recently by the scientists of the Sloan Digital Sky Survey, including Penn State's Donald Schneider, associate professor of astronomy and astrophysics.  "This is an exciting discovery on its own, plus it heralds a tremendously productive decade of discoveries about our universe with the new Sloan Digital Sky Survey Telescope," Schneider says.  Quasars are compact yet very luminous objects thought to be powered by super-massive black holes.  "We are viewing this new quasar as it was when the universe was only about 7% of its current age, and we expect to find many more quasars even farther back in time and space with this new telescope," Schneider adds.

Schneider has been the organizer of the Sloan Digital Sky Survey's quasar science group since its inception in the early 1990s, helping to assure that its scientists achieve the project's research goals for quasars, the most luminous objects in the universe.  He also is one of the principal authors of the paper describing the discovery, recently submitted for publication in the Astronomical Journal.

The quasar previously ranked as the most distant was discovered in 1991 by Schneider and his colleagues Maarten Schmidt of the California Institute of Technology and James Gunn of Princeton University, who is the Project Scientist for the Sloan Survey.  Only about 15,000 quasars have been identified since 1963, when Schmidt first measured a quasar's distance from Earth, but the Sloan Survey is expected to discover over 100 thousand new quasars during the next decade.

More information and high-resolution photos are available at www.sdss.org/news/ releases/19981208.qso.html

Scientists have discovered that too much or too little sodium can be detrimental to the breeding success of mosquitoes and other insects.  Christopher J. Paradise, a Penn State postdoctoral researcher in the Department of Biology, and William A. Dunson, professor emeritus of biology, describe their discovery, which they made while conducting a study on the effect of atmospheric deposition of sulfates, nitrates, and acids on insects breeding in small pools of water, in a recent issue of the journal Annals of the Entomological Society of America.  They performed their study in the Pennsylvania State Gamelands near Sandy Ridge in Centre County.

Paradise and Dunson examined populations of insects living in pockets of water with different ion concentrations in natural and simulated treeholes.  Treeholes often form from stumps left behind after a forest has been completely cut down: when new trunks sprout from a tree stump, the center rots, and water collects in the resulting hole.  Treeholes are common in such secondary-growth forests, occurring at the rate of up to 25 to 30 per acre.  They also are found in neighborhood streets and backyards.  "Treehole communities," as researchers refer to them, consist of aquatic insects such as the eastern treehole mosquito, biting midges, and marsh beetles, among others.

The researchers used simulated treeholes to study the amounts and effects of sodium on insects.  Their simulated treeholes are insulated plastic containers covered with netting and filled with fixed amounts of simulated treehole water, dried treehole sediment, and oak leaves.  All the simulated treeholes, which were exposed to the same temperature and rain conditions, were composed of the same nutrients and water volume, with various controlled levels of sodium.

Paradise and Dunson's research shows a consistent relationship between low sodium levels and high insect population densities in natural treeholes, suggesting that the amount of sodium is depleted by high numbers of insect larvae, or alternatively, that females may choose to lay their eggs in waters lower in sodium.

"The habitat of larval aquatic insects is determined by where the female lays her eggs and the levels of essential nutrients there can affect individual and population growth rates," Paradise explains.  The researchers found that insects sometimes prefer to lay eggs in treeholes with lower sodium levels or higher water levels, and that the amount of sodium in a treehole is dependent on the amounts of leaf litter and water it has, the treehole orientation, the angle of its opening, the size of the opening, and how easily leaf litter and water can drop in.  "Female mosquitoes prefer dark and rough tree walls, horizontal openings, and the presence of organic decay by-products," Paradise says.  They also found, conversely, that mosquitoes actually grow larger in simulated treeholes with higher sodium levels.  "This apparently contradictory finding can result from the need for mosquitoes to absorb sodium during their development and explains how a decrease in sodium concentration can occur if enough mosquitoes are present," Dunson explains.

An additional study performed by Penn State undergraduate biology honors student Michael J. Baltzley, under the direction of Paradise and Dunson, found that the density of the mosquito population, as well as the sodium levels in the treehole, will interact to affect an insect's breeding success.  In small treeholes with the
highest naturally occurring sodium levels and low population densities, the mosquitoes grow faster,
mature quicker, emerge larger, and escape the treehole before it dries during the summer.  In treeholes with very low levels of sodium and high population densities, on the other hand, all the insects grow poorly.  The researchers concluded that there is an ideal range for sodium concentration for insect populations to thrive: too much or too little sodium has negative consequences for developing insects.

So is it a good idea to dump lots of salt in your backyard treeholes?  "No," Paradise says.  "While measuring sodium levels is a good method for predicting the density of a given population of mosquitoes, it is not a good method for control because every single treehole in the area would need to be treated with excess sodium."  "Instead," he suggests, "it's best if people protect themselves from mosquitoes by relatively safe and easy methods like covering up with clothes or burning citronella candles."

This research was funded by the Environmental Protection Agency.

A Penn State biologist who played a leading role in creating an ecology research institute in the Amazon is the head of a group of faculty and students that recently released a report on environmental sustainability at Penn State's University Park campus.  Christopher Uhl, professor of biology, directs the group, which calls itself the "Sustainable PSU Initiative."

The group presented a copy of the 110-page report to Provost John Brighton, who accepted it on behalf of Penn State during a brief ceremony on the steps of the Old Main administration building on the University Park campus.

"A central question motivating our report is: How can Penn State educate citizens to live thoughtfully on our planet?," Uhl says.  "We live in a world of limited resources and how we treat the Earth and each other reverberates throughout the planet, whether we are in Central Pennsylvania or in the Amazon rainforest," he adds.

"Twenty-seven undergraduates from five different colleges at Penn State, two graduate students, two research assistants, and numerous staff and faculty members participated in various aspects of the project," Uhl says.

The report, titled "The Penn State Indicators Report: Students and Faculty Examine the University," examines "sustainability" at Penn State, which it defines as "meeting present needs without compromising the ability of future generations to meet their needs."  It focuses on thirty-four different indicators that consider such things as water and energy use, waste production, recycling, food-purchasing policies, pesticide use, green space converted to parking space, research ethics, and openness in decision making.  "For each indicator, we present data that attempt to gauge if Penn State is moving toward or away from sustainability," Uhl says.  "They are analogous to the vital signs a doctor uses to assess the overall well-being of a patient."

Overall, the report concludes that seven of the thirty-four indicators, such as recycling, pesticide use, and water consumption, are clearly moving toward sustainability.  "For another seven indicators, the situation is strongly nonsustainable with no sign of a turnaround," Uhl says.  "An additional fourteen indicators also reveal clearly nonsustainable practices but show some hints of remedial action, and for the remaining six indicators more data and discussion are needed before a judgement can be reached," he adds.

"Penn State is probably quite typical of other large universities," Uhl comments.  "The report describes many examples of measures that Penn State has taken to become more sustainable.  While reassuring, these steps still fall short of the bold and far-reaching initiatives that will be required to address sustainability issues at Penn State."  The report details thirty specific steps that Penn State might consider in its quest for truly sustainable practices.

Among the report's reviewers at Penn State is Ronald Filippelli, associate dean of the College of Liberal Arts, who comments "This report is a demonstration of the kind of exciting and relevant learning that can take place when students and faculty work collaboratively.  The sustainability project demanded methodological rigor and an interdisciplinary, integrated systems approach to the problem . . . Penn State should be proud of the result."

Uhl adds, "The intent of this report is not simply to supply answers but to raise questions that center on the wisdom of continual growth, research ethics, the openness of decision making, the uncritical acceptance of technology, and the moral responsibilities of the university--questions that all vital institutions should discuss."

Copies of the report are available for purchase nationally through the U. S. Campus Ecology Program of the National Wildlife Federation, a network of several thousand colleges and universities (703-790-4322, Keniry@nwf.org, http://www.nwf.org/campus).  The federation is making the report available as part of its Campus Ecology Toolkit to be used as a model for other large universities nationwide.  Copies also are available for purchase in State College bookstores and at Penn State's Center for Sustainability (814-865-2223).
 

The ancestors of major groups of animal species began populating Earth more than 600 million years earlier than indicated by their fossil remains, according to the largest study on the subject using gene sequences, recently completed at Penn State.  The research suggests that animals have been evolving steadily into different species for at least 1200 million years, which challenges a popular theory known as the Cambrian Explosion that proposes the sudden appearance of most major animal groups, or phyla, 530 million years ago.

A paper describing the research was published in a recent issue of the Proceedings of the Royal Society of London (Series B) by Penn State Undergraduate Student Daniel Y.-C. Wang, Postdoctoral Fellow Sudhir Kumar, and Associate Professor of Biology S. Blair Hedges.

To gauge the pace of evolution, the research team tested hundreds of gene sequences to find those that developed mutations at a constant rate over time.  "Because mutations start occurring at regular intervals in these genes as soon as a new species evolves--like the ticking of a clock--we can use them to trace the evolutionary history of a species back to its actual time of origin," Hedges explains.

By comparing individual genes in pairs of species, the researchers identified 75 nuclear genes that had accumulated mutations at a fairly constant rate relative to one another during their evolution.  The genes were from species representing three major taxonomic groups, or phyla, of animals (arthropods, chordates, and nematodes), plus plants and fungi.

The scientists then calibrated these molecular clocks to an evolutionary event well established by fossil studies--the divergence of birds and mammals about 310 million years ago.  "A clock isn't any good unless it is calibrated to a time that everyone else agrees on," Hedges explains, "and just about everyone agrees on the date when reptilian ancestors of birds and mammals appeared because it is based on well-accepted studies of fossils."  Using this date as a secure calibration point--and the mutation rate for each of the constant-rate genes as a timing device--the researchers were able to determine how long ago each of the species originated.

"Not only are all these genes telling us that a wealth of animal species in at least three phyla were already on Earth millions of years before their fossils start appearing," Hedges says, "but they also are telling us when three of the major kingdoms of living things--animals, plants, and fungi--first diverged from a common ancestor and began evolving down separate evolutionary paths."  That date--about 1.6 billion years ago--is the earliest yet obtained by gene studies for this evolutionary event, according to Hedges.

The Penn State team used more than twice as many genes to date the origin of the three major animal phyla as had been used in any other study since gene sequences first became available in the Genbank public databases maintained by the National Institutes of Health during the 1970s.  "We wanted to have so much data that the conclusions from our study of this controversial issue could be very robust," Hedges comments.  Earlier studies using many fewer genes were disturbing to some researchers because they yielded a wide range of dates for the origin of animal species, although all the gene studies agreed that the event occurred well before the Cambrian period.  "Our methodology and our larger data set should have had a stabilizing effect; and in fact, our study resulted in a date intermediate between the earlier estimates," Hedges says.

If the results of his team's genetic study are correct, Hedges says the scientific question must change from "How did all these species evolve so suddenly early in the Cambrian period?" to "Why don't we see any fossils of these species long before the Cambrian period?"  Among the suggested answers are that changes in the Earth's atmosphere led to the development of hard external skeletons in animals that had only soft external skeletons before the Cambrian period.  "Hard body parts like external skeletons are most likely to become fossils," Hedges explains.  Species not likely to fossilize, like earthworms, typically live and die without leaving a trace of their existence--except in the genes of their descendants.

Another hypothesis is that many species of animals with skeletons were living on Earth before the Cambrian period, but they were so small that their fossils have not yet been found.  "The further back in time you want to look in the fossil record, the fewer places there are on Earth to look," Hedges explains.  Fossils have to be safely encased in sedimentary rock, which, over time, melts or becomes deformed by the movement of the Earth's crust.  Sedimentary rocks over 3 billion years old are very rare.  "If we can find very-old and very-fine-grained phosphate sediments, which can preserve even soft bodies, we might have the potential of finding fossils of these early animals, even if they were only microscopic in size,"  Hedges says.  "We seem to be missing the fossils of a lot of species."

Hedges says his research might be useful for finding life on other planets.  "If we can learn when different stages of life evolved on Earth, we can compare those dates to events in the chemical evolution of Earth's atmosphere and ocean, such as when oxygen and other important gases increased," Hedges explains.  Research with this goal is an important focus in Penn State's Astrobiology Research Center.  "Our goal is to see if the early history of life on Earth can give us clues for how to predict life on other planets and in other solar systems," Hedges says.  "We hope to be able to predict the kinds of lifeforms that are likely to exist on other planets, based on those that existed during Earth's history, just by measuring the chemical content of the planet's atmosphere."

This research was supported by grants from the National Science Foundation and the National Aeronautics and Space Administration.
 

Overwhelming evidence from the largest evolutionary study of gene sequences ever performed shows that the major groups of mammals emerged well before the extinction of the dinosaurs, according to Penn State researchers Sudhir Kumar, postdoctoral fellow, and S. Blair Hedges, associate professor of biology, whose research was published in a recent issue of the journal Nature.

"The evolution of mammals appears to have occurred gradually by the isolation of breeding groups when the continents broke apart, not suddenly by the rapid filling of ecological niches left vacant when the dinosaurs became extinct," Hedges says.  The massive gene study suggests that modern orders of mammals first evolved when the continents were separating during the Cretaceous era about 100 million years ago--much earlier than some previous estimates based on fossil studies, which link the evolutionary event to mass extinctions 65 million years ago.

"This is the first time we ever have been able to estimate when all these lifeforms appeared on Earth," Hedges says.  "Fossils can't give us this information, partly because there are huge periods of Earth's history from which not enough fossils have been found to make reliable estimates."

To gauge the pace of evolution, Kumar and Hedges mined a burgeoning collection of gene sequences being accumulated at Genbank, the public genetic databases maintained by the National Institutes of Health.  They sifted through many thousands of vertebrate gene sequences from hundreds of species to find those that develop mutations at a constant rate over time.  These genes can be used as a timing device for estimating the date of each species' evolution.  "During the past few years there has been a tremendous explosion in the number of known gene sequences, so we had ten times as much data to work with as we did just two years ago," says Hedges, who published a similar but much smaller study with Kumar and others in 1996.

Hedges says that, in contrast to the use of gene sequences, the use of fossils to estimate when two species emerged from their last common ancestor necessarily results in an underestimation.  "The body structure of a fossilized animal had to have evolved at some earlier date before its lifetime--in many cases, it was many generations and many millions of years earlier.  But genes are different--their clock-like mutations start ticking away as soon as a new species evolves, so the molecular clock takes you back to the actual time of origin."

The researchers found that their molecular clock yielded origin dates similar to those based on fossil dating for many species, but for others the genetic clues lead back to a much earlier time.  For example, Hedges says "the fossil record for rodents says that mouse and rat split only 10 million years ago, but we have 343 genes in this study telling us that mouse and rat split from their last common ancestor 41 million years ago--four times as long.  The rodent fossil record appears to have some major gaps," Hedges says.

By comparing individual genes in pairs of species, the researchers identified 658 genes from 207 vertebrate species that had accumulated mutations at a fairly constant rate relative to one another during their evolution.  The scientists then calibrated this molecular clock to an evolutionary event well established by fossil studies--the divergence of birds and mammals about 310 million years ago.  "A clock isn't any good unless it is calibrated to a time that everyone else agrees on," Hedges explains, "and just about everyone agrees on the date when reptilian ancestors of birds and mammals appeared because it is based on well-accepted studies of fossils."  Using this date as a secure calibration point--and the mutation rate for each of the constant-rate genes as a timing device--the researchers were able to determine how long ago each vertebrate order originated.

"We mined a lot of data by sorting through all the gene sequences in Genbank to find the ones that fit our criteria," says Kumar.  "The only way we could have analyzed all the data so quickly was by taking a 'bioinformatic' approach," he says, explaining that they used computers as well as manual methods to compare thousands of gene sequences and test them for rate constancy using different parameters.  "It very easily is the largest evolutionary study of gene sequences ever done for estimating the origin of so many species," Kumar comments.

Very few fossils resembling modern mammals or other vertebrates have been found in rocks formed during the Cretaceous period, says Hedges, partly because paleontologists hardly ever look for mammals in rocks that old.  "There has not been enough convincing evidence until now for paleontologists to invest their time and money looking for mammal fossils in a time before the dinosaurs became extinct," Hedges says.  In addition, many scientists believe that a large number of species suddenly sprang into existence at the very end of the Cretaceous period.

Hedges says he hopes, as a result of this research, that paleontologists will now begin searching for mammals in geological strata where they have never looked before.  "We are saying mammals definitely were living on Earth during the Cretaceous period from 70 to 100 million years ago.  We don't yet know what they look like, but from the genes of their descendants we now know that they were there."

This research was supported in part by the National Institutes of Health and the National Science Foundation.

The world's most land-loving crab, a thin and delicate Jamaican species that spends its entire life in a tree, made a surprisingly rapid evolutionary transformation from its large and rugged ocean-dwelling ancestors, according to genetic research published in a recent issue of the journal Nature by an international team of biologists.

"These very unusual crabs, which are the most terrestrial of any in the world, live in little pockets of rainwater inside bromeliad plants, which grow on the branches of tropical trees," says S. Blair Hedges, an evolutionary biologist at Penn State and a member of the research team.  The tiny bromeliad crabs are less than an inch long and are thin enough to squeeze between the leaves at the base of the bromeliad plant, where rainwater collects.  The researchers say these crabs are by far the most attentive mothers of all known crab species and the only ones known that actively feed and care for larvae and juveniles during the several months they spend in their rainwater nursery.  "The mother crab manipulates water quality by removing debris, by circulating the water to add oxygen to it, and by carrying empty snail shells into the water to buffer the pH levels and add calcium," Hedges says.

Because the bromeliad crab looks and behaves so differently from its ocean-dwelling neighbors, scientists thought the two species must have required a long time to evolve from their last common ancestor--on the order of 50 million years or so.  Other scientists thought the tiny crab might, instead, have somehow immigrated from Southeast Asia or Indonesia, where there are some freshwater species that also care for their young, although not to the unusual degree of the bromeliad crab.  "We decided to find out how the Jamaican land crabs are related to other species and when they came to the island by looking at their genes," Hedges says.  "We found that the bromeliad crab--and also the eight other species of Jamaican land crabs--are not related to crabs on the other side of the world but have evolved from one common Jamaican marine ancestor very recently--only 4 million years ago."

The research team includes Hedges, Christoph D. Schubart, of the University of Southwestern Louisiana, and Rudolf Diesel, of Bielefeld University in Germany.  Schubart collected 22 crab species from Jamaica and surrounding areas, including Venezuela and Panama, then brought them to Penn State for genetic research in Hedges's lab.  "We sequenced two genes from each of these species, which gave us a little over a thousand base pairs--enough to say statistically that all the terrestrial Jamaican crabs form a single group," Hedges says.

The genes used in the study have accumulated mutations at a fairly constant rate relative to one another during their evolution, so the researchers could use the changes like the ticking of a molecular clock to trace the history of each species back to its origin.  "The clock-like mutations in the gene sequences start ticking away as soon as a new species evolves, so the molecular clock takes you back to the actual time of origin of the species," Hedges explains.

The scientists calibrated this molecular clock to an evolutionary event well established by geological studies, the closing of the Panama land bridge between North and South America 3.1 million years ago that separated species of marine crabs into two breeding groups--those living on the Caribbean side of Panama and those living on the Pacific side.  Using this date as a secure calibration point--and the mutation rate for the two genes from related crabs on either side of Panama as a timing device--the researchers were able to determine how long ago all of their 22 crab species originated.

"We found that these Jamaican land crabs began evolving only 4 million years ago, so their evolution has been quite rapid," Hedges says.  "This date makes sense because it corresponds to a time in Jamaica's geologic history when the land had risen far enough out of the sea to provide new ecological niches for the ancestral marine crab that began evolving strategies for living entirely on the land," he explains.

The scientists also determined how closely each of the 22 species is related to the others by comparing the molecular sequences that make up each of the two genes and then determining which are most similar.  "We found that the closest relative of the Jamaican terrestrial crabs is a Jamaican marine crab," Hedges says.

"Jamaican land crabs look and act very different from Jamaican marine crabs, yet they have been evolving separately for the same amount of time as the marine crabs we used for our calibration on either side of Panama, which have remained almost identical," Hedges says.  "Such rapid adaptation to a new ecological niche and rapid radiation of new species is not common in nature, but it apparently has occurred much more quickly than we had thought possible in these Jamaican terrestrial crabs."

This research was sponsored by the German Science Foundation and the U. S. National Science Foundation.

The Penn State Department of Astronomy and Astrophysics has been selected as one of five finalists to design and build a space observatory satellite in NASA's medium-class Explorer (MIDEX) program.  Penn State's proposed space observatory is the "Swift Gamma Ray Burst Explorer," a $135 million satellite that is a joint project with the Goddard Space Flight Center.

Penn State and the other four finalist teams were judged to have the best science value among 35 proposals submitted to NASA in August 1998.  Each team has received $350,000 to conduct a four-month implementation feasibility study focused on cost, management, and technical plans, including educational outreach, and small-business involvement.  NASA will evaluate the feasibility studies and select two winners in September 1999.

If Penn State's Swift Gamma Ray Burst Explorer is one of the observatories NASA decides to build, it will be launched into Earth orbit in 2003 or 2004.  Its mission is to study gamma ray bursts--gigantic explosions that outshine the rest of the Universe when they occur unpredictably in distant galaxies--whose underlying nature and cause are a mystery.  Department of Astronomy and Astrophysics faculty involved in this project include Penn State Principal Investigator John Nousek and co-investigators David Burrows, Eric Feigelson, Gordon Garmire, Peter Mészáros, and Donald Schneider.

"Gamma-ray bursts are among the most exciting topics in current astrophysics," Nousek comments.  "We have a lot of hard work to do to qualify for one of the launch opportunities, but if we are successful we will become a focus, on a global scale, for Gamma-ray-burst discoveries."

NASA's MIDEX program supports the rapid development of lower-cost scientific spacecraft with highly focused missions.  "Once launched, these missions will provide insights into some of the biggest questions in space science," said Ed Weiler, Associate Administrator for Space Science at NASA Headquarters.  In addition to Penn State's proposal to observe the largest explosions  in the Universe, the other proposed observatories have missions to study the brightest galaxies in the Universe, understand the link between the Earth's aurora and the solar wind, search for planetary systems around 40 million stars, and investigate magnetic eruptions in the Sun's corona.

The other proposed observatories selected as finalists include the Next Generation Sky Survey, a project of the University of California; the Full-sky Astrometric Mapping Explorer, a project of the U.S. Naval Observatory; the Auroral Multiscale Midex Mission, a project of the Johns Hopkins University Applied Physics Laboratory; and the Advanced Solar Coronal Explorer , a project of the Harvard-Smithsonian Center for Astrophysics.

Four Pennsylvania middle-school and high-school science teachers spent part of the summer studying active volcanoes and hydrothermal vents more than a mile below the surface of the ocean, thanks to financial support from Penn State, the National Science Foundation, and the University of Washington.

Sandra Ivey, of Bangor Area Senior High School in Bangor; Patti Peterson, of Palisades High School in Richlandtown; Ellen Wright, of Perry Traditional Academy in Pittsburgh; and Roy DeRemer, of Warwick Middle School in Lititz, were among a handful of U.S. teachers selected to participate in one of two research cruises as part of the program based at the University of Washington titled Research and Education: Volcanoes, Exploration, and Life (REVEL).  One cruise was filmed for use on the television documentary program, NOVA.

The REVEL program is directed by Veronique Robigou at the University of Washington.  Penn State Associate Professor of BiologyCharles Fisher, an active REVEL participant and organizer for the past three years and the chief scientist for the program's most recent expedition, obtained the funding to include Pennsylvania teachers for the first time this year.

Fisher also is one of the principal scientists in a long-term project to establish a biological observatory at this research site in "inner space" on the Juan de Fuca Ridge submarine spreading center 200 miles off the coasts of Oregon, Washington, and Canada, where new sea floor is continuously being created.

"The teachers got about 20 days of professional development, at sea and in workshops, which they began sharing with their students in Pennsylvania this fall," Fisher says.  "Grants from the Penn State's Eberly College of Science and the Penn State Outreach and Cooperative Extension office, along with support from the National Science Foundation, made it possible for these teachers to be with us on this cruise," Fisher says.

They joined an international team of marine biologists, chemists and geologists in a multi-year effort to understand how communities of animals live on and around mineral chimneys known as "black smokers" and other structures associated with underwater volcanoes.  "We had on board a very diverse group of scientists, including ecologists, physiologists, microbiologists, chemists, and geologists, who the teachers worked with around the clock on studies involving samples collected from the sea floor," Fisher says.

Some of the teachers were on a cruise led by Fisher that used as its principal research tool the three-seater submarine, Alvin, which the scientists used to set up experiments on the sea floor, collect samples of biological and geological materials, and take video and still-camera images.  The other cruise, led by John Delaney and Deborah Kelley of the University of Washington, had as its principal research tool the remotely operated vehicle, ROPOS, which the researchers used to bring up from the sea floor, for the first time, several very large black smoker sulfide chimneys--the largest of which is 1.5 meters tall.  Several of the black smokers are on exhibit in the American Museum of Natural History in New York this spring.

"It was satisfying to watch the teachers immediately combining their shipboard experience with their special skills to put together the beginnings of lesson plans," Fisher says.  The teachers plan to share the new lesson plans they develop with other Pennsylvania and U.S. teachers--not only the facts about the hydrothermal vents but also their enthusiasm for the scientific process of research.

"I will be going to every school in our district to do presentations for students and faculty and have also been asked to go to schools in Bethlehem, Quakertown, Nazareth, Marple Newtown, and Upper Merion, plus some colleges and businesses in Pennsylvania," says teacher Sande Ivey, who also plans to continue working in her classroom on the research project she started at sea.  "My 'pay back' to Penn State will be to do the very best job that I can to teach students and faculty what I learned this summer," she adds.

"Using my REVEL experience of working with scientists doing frontier research in one of the most extreme environments on Earth, I hope to model the process of 'doing' science for my students, several of whom will be actively involved with further study of the problems investigated on the ship," says teacher Pat Peterson.  "I believe that REVEL specifically addresses the objectives that the Commonwealth of Pennsylvania has recently adopted for use in the development of curriculum in public education in our state--besides, it was really cool stuff for a little old schoolteacher from Pennsylvania to get to do," she adds.

"A few of the classroom activities that I see my students becoming involved in as a direct result of this expedition are comparing and contrasting Western Pennsylvania ecosystems to the hydrothermal- vent ecosystem, using RNA and DNA data from the vent organisms to analyze the amount of protein synthesis taking place, and using DNA fingerprinting data to determine if the organisms at different vents are the same species," says teacher Ellen Wright.  "My students also will benefit because I have a new network of scientists and teachers with whom to collaborate," she says.

Fisher says he is thoroughly pleased with both the scientific success of the expedition and the success of the REVEL program.  "My own enthusiasm for this program stems from my belief that it is never too soon to excite a young mind with the pleasures and rewards of scientific inquiry. I am thrilled that we can contribute to this goal while also enriching our scientific program."

Sponsors of the REVEL program include the National Science Foundation, the University of Washington, the American Museum of Natural History, and Penn State.  More information about the teachers is available at the REVEL project site on the World Wide Web at http://www.ocean.washington.edu/outreach/revel/subexframework.html .

A new catalyst dramatically improves the performance of methanol-air fuel cells, which could provide a more practical power source than batteries or the fuel cells powered by hydrogen that are used in space missions, according to research published in a recent issue of the journal Science.

"The hydrogen fuel cells that have flown on space missions since Gemini are not practical for most applications on Earth because they use catalysts and electrolytes that work only with very pure hydrogen, which is expensive to make and is hard to store and transport," explains Thomas E. Mallouk, professor of chemistry at Penn State and a member of the research team.  "Nobody wants to carry a tank of compressed hydrogen with their laptop computer, and they would prefer not to have one in their car.  These problems have motivated our research on fuel cells that run on renewable, liquid fuels," Mallouk says.

Along with Mallouk, the research team includes Penn State graduate student Erik Reddington and undergraduate Anthony Sapienza; graduate students Bogdan Gurau and Rameshkrishnan Viswanathan and Associate Professor of Chemical and Environmental Engineering Eugene S. Smotkin, at the Illinois Institute of Technology (IIT); and S. Sarangapani of ICET, Inc., in Norwood, Massachusetts.

Fuel cells derive electrical energy directly from power-packed chemicals such as hydrogen, alcohols, and natural gas.  In so doing, they side-step a basic thermodynamic limit on the efficiency of engines that burn fuel to make heat, and then use the heat to generate electricity.  "Because fuel cells operate like batteries, they are inherently efficient power conversion devices," says Mallouk.

The new research involves fuel cells that use methyl alcohol, or methanol--a liquid fuel that can be made cheaply from biomass or from fossil reserves such as coal, oil, or natural gas.  "Because it is compatible with existing delivery systems for liquid fuels, methanol is used, for example, by race cars at the Indianapolis 500 that already burn methanol in their engines," Mallouk says.  For fuel cells, methanol presents a special problem because its oxidation in the cell poisons the catalytic electrode surface. "The platinum catalysts that work so well in hydrogen fuel cells are basically useless for methanol," Smotkin says.  "They do not adsorb water, which is needed to oxidize away the carbon monoxide that builds up on the platinum surface.  That is why platinum alloys containing elements that bind the oxygen atom in water are much better catalysts."  Up to now, a platinum-ruthenium alloy has been the best known catalyst for methanol fuel cells.  The new catalyst, a quaternary alloy containing platinum, ruthenium, osmium, and iridium, is between 40% and 100% better, depending on the power demand on the cell and is particularly good under high current/high power conditions, the researchers say.

The idea for looking at these complex catalyst compositions came from a paper published by Smotkin's group in 1995 in the Journal of the Electrochemical Society.  "They correlated the ability of an alloying element to bind water with catalyst performance," says Mallouk.  "This gave them the idea that three elements might be better than two in a catalyst.  Further, they had a good idea of which elements to mix together."  However, making and testing these alloys was a time-consuming process, which became worse as more elements were added.  "To do a reasonable job at testing combinations of four elements, you would have to look at hundreds of catalysts," says Mallouk.  "This could not be done in a reasonable time by making them serially, and further, it would not be much fun for the graduate student who had to do it," he says.

Instead, the Penn State group devised a method for making and testing hundreds of different catalysts at the same time.  Using an ink-jet printer, they printed dots of metal-salt mixtures onto a large carbon electrode.  Each dot, which was about the size of a lower-case letter "o," contained a slightly different mixture of five elements: platinum, ruthenium, osmium, iridium, and rhodium.  All the dots were converted into alloy catalysts by a solution process similar to that used to make bulk fuel cell catalysts.  To determine the catalytic activity of each dot, the researchers chemically converted the electrical current to an optical signal.

"The good catalysts are lit up, using a trick that is similar to a litmus test," says Mallouk, "Wherever methanol is oxidized on the array electrode, it generates acid.  A fluorescent acid-base indicator in the solution above the array pinpoints the most active dots, where the concentration of acid is highest."  Using this method, the Penn State group was able to determine quickly where the best catalysts lay in a vast landscape of compositions.  They transmitted the compositions to Sarangapani at ICET, who made larger quantities of the catalysts for testing in methanol-air fuel cells by Smotkin and coworkers at IIT.

While there is still room for improvement in these fuel cells, Mallouk is encouraged by the results.  "We now have a method to look far and wide in composition space for new catalysts.  By correlating the composition/activity map with a microscopic analysis of catalyst structure, we should be able to learn something about what makes the good catalysts work," he says.  "Also, the fact that we found a hot new composition in a rather limited search suggests that there will be other--hopefully better--ones out there."

This research was supported by the Office of Naval Research, the Army Research Office, and the Defense Advanced Research Projects Agency.

Newly discovered African fossils could resolve questions over the age and evolution of a species thought to be the most ancient known upright-walking ancestor of humans, according to research published in a recent issue of the journal Nature.

The research team includes Meave G. Leakey, curator of paleontology at the National Museums of Kenya; Craig S. Feibel, assistant professor of anthropology at Rutgers University; Ian McDougall, professor of earth sciences at the Australian National University; Carol Ward, assistant professor of anthropology at the University of Missouri; and Alan C. Walker, distinguished professor of anthropology and biology at Penn State.  The researchers, who first named the new species Australopithecus anamensis, in a paper published in Nature in 1995 based on 22 fossils discovered in northern Kenya, now have unearthed 38 additional fossils that paint a more complete picture of the species.  Some scientists questioned the antiquity of the fossil bones described in the 1995 paper, which were found sandwiched at different depths between layers of rock and ancient soils, because a definite time of origin could not then be measured for the youngest layer.  "The fossils found in younger deposits were the most human-looking, so some people said we could have two species instead of just one--an older one and a much younger one," Walker says.

"In 1995 we could not firmly establish the age of the youngest geologic layer associated with these fossils because the best dating technique, the 40 Argon/39 Argon method, needs crystals and this particular layer is mostly powdery ash," Walker explains.  "Since then--after much sifting through the ashes--we have managed to get enough good crystals to determine quite firmly that these fossils are between 4.1 and 4.2 million years old," he says.  "We also have discovered 38 more fossils at this site that clearly show us how very primitive this species was."

Walker says he is interested in the Australopithecus anamensis species because it is an important branch on the human family tree.  According to Walker, the new fossils reveal that the ancient species had primitive jaws shaped more like a chimpanzee's than like a modern human's.  It also had another characteristically primitive feature known as sexual dimorphism--large differences between the sexes in overall body size and the shape of certain body parts such as teeth.  "These males have very large canine teeth, while we humans have lost our canine dimorphism, to a large extent," Walker explains.  "Human males still do have slightly bigger canines, on average, and their enamel is thinner than a female's--a characteristic of male apes, which sharpen their teeth to use as weapons," he adds.  Among the new fossils is a wrist bone, which Walker says has the primitive features of a chimpanzee's.  On the other hand, he says, the leg bone is more like a modern human's, with a structure that allowed the species to walk upright on two legs instead of on all fours like a chimpanzee.  "It just shows you that we don't evolve all at once in every part of our body--we do it in little bits and pieces like a mosaic, depending on which piece natural selection is acting on at the time," he explains.

Although some scientists believe that the human family tree is bushy at its base, with multiple species evolving at the same time, Walker says all the early fossils discovered so far support a more tree-like picture of evolution for hominids--the ancient ancestors on the human family tree.  "We don't yet have any convincing evidence early in the fossil record of multiple hominid species," Walker says.  "The simplest explanation for the hominid fossil record from 4.5 to 3 million years ago is that there is only one single evolving species and that it had a primitive degree of body-size sexual dimorphism."  He adds, "eventually we will find the last common ancestor of chimps and humans."

This research was supported by the National Geographic Society in Washington, D.C.; the U.S. National Science Foundation; the National Museum of Kenya; the Leakey Foundation; the Australian Institute of Nuclear Science and Engineering; the Australian Nuclear Science and Technology Organization, and Caltex in Kenya.

Catalytica Pharmaceuticals, Inc., a subsidiary of Catalytica, Inc. has signed exclusive license and development agreements with Penn State for new chiral pharmaceutical process technology with important potential applications for the development of processes for a broad spectrum of new drugs.  The new agreement grants Catalytica exclusive worldwide rights to commercial development of the University's work in asymmetric catalysis as developed by Xumu Zhang, assistant professor of chemistry.  The license covers all applications of the technology in the manufacture of pharmaceutical and animal-health products.  The development agreement includes the ongoing sponsorship of research in Zhang's laboratory by Catalytica in these areas.

Zhang's recent work in asymmetric catalysis is aimed at facilitating the development of efficient, high-yield processes for the manufacture of pharmaceutical compounds known as chiral drugs, a broad category of medications whose therapeutic effectiveness is dependent on the shape and configuration of a drug molecule in addition to its chemical composition.

Though chemically identical, chiral molecules may take either of two mirror-image forms and are therefore said to be either "left-handed" or "right-handed," depending upon the configuration of the molecule in space.  The effectiveness of pharmaceuticals often is based on the precise matching of the drug molecule with the structure of receptors inside the body.  As a result, it is frequently the only one of the two mirror-image forms of a molecule that provides therapeutic results.  Techniques for producing only this useful configuration, like Zhang's recent work, have the ability to increase the efficiency and lower the cost of the drug-manufacturing process.

According to James A. Cusumano, Chairman of Catalytica and Chief Executive Officer of Catalytica Pharmaceuticals, the new asymmetric catalysis technology has applications for many drugs currently in development. "We see this technology as offering a significant potential benefit for the production of pharmaceuticals for which only one specific chiral form of the drug molecule is of therapeutic interest.  We look forward to continued innovation from Penn State and Dr. Zhang in this field and to our mutual opportunity in exploiting this technology."

Thomas J. Monahan, Director of Penn State's Intellectual Property Office, explaining the choice of Catalytica Pharmaceuticals as an exclusive licensee, said the company is "an ideal partner for this technology by virtue of Catalytica's commitment to process development as well as the opportunity for commercialization.  The entrepreneurial culture of Catalytica is also well suited to compliment the continued research program in Professor Zhang's laboratories."

Catalytica Inc., through its subsidiaries, provides catalytic technologies and advanced products which improve manufacturing processes and solves environmental problems economically.  The three subsidiaries are Catalytica Pharmaceuticals, Inc., which serves the healthcare industry; Catalytica Combustion Systems, Inc., which produces the XONONTM combustion technology for the energy market; and Catalytica Advanced Technologies, Inc., which creates new catalytic technologies.

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