A new technique using near-infrared images, obtained with ESO’s 3.58-metre New Technology Telescope (NTT), allows astronomers to see through the opaque dust lanes of the giant cannibal galaxy Centaurus A, unveiling its “last meal” in unprecedented detail — a smaller spiral galaxy, currently twisted and warped. This amazing image also shows thousands of star clusters, strewn like glittering gems, churning inside Centaurus A.

Comparison between a visible-light image (left) of Centaurus A, as seen with the Wide-Field Imager on the MPG/ESO 2.2-metre telescope, and a near-infared view (right) obtained with the SOFI instrument on ESO’s New Technology Telescope, also at La Silla. (ESO)

Centaurus A (NGC 5128) is the nearest giant, elliptical galaxy, at a distance of about 11 million light-years. One of the most studied objects in the southern sky, by 1847 the unique appearance of this galaxy had already caught the attention of the famous British astronomer John Herschel, who catalogued the southern skies and made a comprehensive list of nebulae.

Herschel could not know, however, that this beautiful and spectacular appearance is due to an opaque dust lane that covers the central part of the galaxy. This dust is thought to be the remains of a cosmic merger between a giant elliptical galaxy and a smaller spiral galaxy full of dust.

Between 200 and 700 million years ago, this galaxy is indeed believed to have consumed a smaller spiral, gas-rich galaxy — the contents of which appear to be churning inside Centaurus A’s core, likely triggering new generations of stars.

First glimpses of the “leftovers” of this meal were obtained thanks to observations with the ESA Infrared Space Observatory , which revealed a 16 500 light-year-wide structure, very similar to that of a small barred galaxy. More recently, NASA’s Spitzer Space Telescope resolved this structure into a parallelogram, which can be explained as the remnant of a gas-rich spiral galaxy falling into an elliptical galaxy and becoming twisted and warped in the process. Galaxy merging is the most common mechanism to explain the formation of such giant elliptical galaxies.

The new SOFI images, obtained with the 3.58-metre New Technology Telescope at ESO’s La Silla Observatory, allow astronomers to get an even sharper view of the structure of this galaxy, completely free of obscuring dust. The original images, obtained by observing in the near-infrared through three different filters (J, H, K) were combined using a new technique that removes the dark, screening effect of the dust, providing a clear view of the centre of this galaxy.

What the astronomers found was surprising: “There is a clear ring of stars and clusters hidden behind the dust lanes, and our images provide an unprecedentedly detailed view toward it,” says Jouni Kainulainen, lead author of the paper reporting these results. “Further analysis of this structure will provide important clues on how the merging process occurred and what has been the role of star formation during it.”

The research team is excited about the possibilities this new technique opens: “These are the first steps in the development of a new technique that has the potential to trace giant clouds of gas in other galaxies at high resolution and in a cost-effective way,” explains co-author João Alves. “Knowing how these giant clouds form and evolve is to understand how stars form in galaxies.”

This image of the central parts of Centaurus A reveals the parallelogram-shaped remains of a smaller galaxy that was gulped down about 200 to 700 million years ago. The image is based on data collected with the SOFI instrument on ESO’s New Technology Telescope at La Silla.(ESO)

Looking forward to the new, planned telescopes, both on the ground and in space, “this technique is very complementary to the radio data ALMA will collect on nearby galaxies, and at the same time it poses interesting avenues of research for extragalactic stellar populations with the future European Extremely Large Telescope and the James Webb Space Telescope, as dust is omnipresent in galaxies,” says co-author Yuri Beletsky.

Previous observations done with ISAAC on the VLT (ESO 04/01) have revealed that a supermassive black hole lurks inside Centaurus A. Its mass is about 200 million times the mass of our Sun, or 50 times more massive than the one that lies at the centre of our Milky Way. In contrast to our own galaxy, the supermassive black hole in Centaurus A is continuously fed by material falling onto into it, making the giant galaxy a very active one. Centaurus A is in fact one of the brightest radio sources in the sky (hence the “A” in its name). Jets of high energy particles from the centre are also observed in radio and X-ray images.

The new image of Centaurus A is a wonderful example of how frontier science can be combined with aesthetic aspects. Fine images of Centaurus A have been obtained in the past with ESO’s Very Large Telescope (ESO PR Photo 05b/00) and with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at La Silla.

This research was presented in a paper in Astronomy and Astrophysics (vol. 502): “Uncovering the kiloparsec-scale stellar ring of NGC5128”, by J.T. Kainulainen et al.

The team is composed of J. T. Kainulainen (University of Helsinki, Finland, and MPIA, Germany), J. F. Alves (Calar Alto Observatory, Spain and University of Vienna, Austria), Y. Beletsky (ESO), J. Ascenso (Harvard-Smithsonian Center for Astrophysics, USA), J. M. Kainulainen (TKK/Department of Radio Science and Engineering, Finland), A. Amorim, J. Lima, F. D. Santos, and A. Moitinho (SIM-IDL, University of Lisbon, Portugal), R. Marques and J. Pinhão (University of Coimbra, Portugal), and J. Rebordão (INETI, Amadora, Portugal).

SOFI (Son of ISAAC) is an infrared spectro-imager attached to ESO’s 3.58-metre New Technology Telescope (NTT) and a simplified version of the Short Wavelength arm of ISAAC on the Very Large Telescope.

- ESO, The European Southern Observatory -

(CERN)

“It’s great to see beam circulating in the LHC again,” said CERN Director General Rolf Heuer. “We’ve still got some way to go before physics can begin, but with this milestone we’re well on the way.”

The LHC circulated its first beams on 10 September 2008, but suffered a serious malfunction nine days later. A failure in an electrical connection led to serious damage, and CERN has spent over a year repairing and consolidating the machine to ensure that such an incident cannot happen again.

“The LHC is a far better understood machine than it was a year ago,” said CERN’s Director for Accelerators, Steve Myers. “We’ve learned from our experience, and engineered the technology that allows us to move on. That’s how progress is made.”

Recommissioning the LHC began in the summer, and successive milestones have regularly been passed since then. The LHC reached its operating temperature of 1.9 Kelvin, or about -271 Celsius, on 8 October. Particles were injected on 23 October, but not circulated. A beam was steered through three octants of the machine on 7 November, and circulating beams have now been re-established. The next important milestone will be low-energy collisions, expected in about a week from now. These will give the experimental collaborations their first collision data, enabling important calibration work to be carried out. This is significant, since up to now, all the data they have recorded comes from cosmic rays. Ramping the beams to high energy will follow in preparation for collisions at 7 TeV (3.5 TeV per beam) next year.

Particle physics is a global endeavour, and CERN has received support from around the world in getting the LHC up and running again.

“It’s been a herculean effort to get to where we are today,” said Myers. “I’d like to thank all those who have taken part, from CERN and from our partner institutions around the world.”

^1. CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

- CERN, the European Organization for Nuclear Research -

Pioneer-Venus visible-light image, and Magellan radar view of Venus. Credit: NASA/JPL/RPIF/DLR.

“Carrying out these observations was a great challenge, as SCIAMACHY was not actually designed for such measurements,” Dr. Manfred Gottwald, responsible for SCIAMACHY at the DLR Remote Sensing Technology Institute (Institut für Methodik der Fernerkundung; IMF), said. “We were surprised how excellently everything worked despite that,” his colleague at the institute, Dr. Sanders Slijkhuis, the specialist responsible for calibrating the instrument, added.

SCIAMACHY on Envisat, Venus Express and COROT complement one another

The Venus observations by SCIAMACHY are useful in two respects. On the one hand, they support the in-situ measurements by the Venus Express space probe of the European Space Agency (ESA), which has been orbiting our neighbouring planet since 2006. Venus Express is studying the dense atmosphere of Venus with great precision using the SPICAV and VIRTIS spectrometers. SCIAMACHY and Venus Express are observing Venus under different viewing geometries and lighting conditions, so that their results complement one another well. In addition, SCIAMACHY’s Venus observations are a further test of the way that an Earth-like planet presents itself spectrally when observed from a great distance.

Since the first extra-solar planets – that is, planets orbiting stars other than our Sun – were discovered in the mid-1990s, the search for Earth-like companions of stars similar to the Sun, in other words a ’second Earth’, has been one of the great challenges in astronomy. Currently, however, most of the so-called exoplanets that have been found are giant gas planets rather like Jupiter. In 2008, researchers succeeded for the first time in discovering a possible Earth-like exoplanet using the CoRoT (Convection, Rotation and Planetary Transits) space telescope, a project in which the DLR is also involved (see article CoRoT discovers extrasolar rocky planets in the right column). But in the near future, small Earth-like planets could also come within reach using improved telescopes. However, they will always appear as small dots due to the enormous distances involved. The spectral analysis of the central star’s light when scattered by the exoplanets and their own thermal radiation emissions could provide information as to whether they might be suitable for harbouring life. Hence, observations of the known planets in our solar system provide an excellent experimental environment for gaining experience with regard to the interpretation of spectral signatures of Earth-like bodies.

Earth observation satellite ENVISAT. Credit: ESA.

DLR planetary researchers pleased about interdisciplinary approach

The observations of Venus, with its hot and hostile environment – surrounded by a dense carbon dioxide atmosphere – can provide outstanding comparative data in our immediate cosmic neighbourhood for the analysis of the atmosphere of exoplanets. “As planetary researchers, we are of course very pleased about these additional measurements from a mission whose aim is actually Earth observation,” Prof. Tilman Spohn, Director of the DLR Institute of Planetary Research (Institut für Planetenforschung) in Berlin-Adlershof, says. He adds: “It is excellent that these data from SCIAMACHY were picked up. They help us to evaluate the data supplied by our experiments on the planetary missions.”

“We are very impressed by the SCIAMACHY observations,” Prof. Heike Rauer, also from the DLR Institute of Planetary Research and the leader of the project through which DLR is involved in the search for exoplanets with CoRoT, said happily. “The new results illustrate excellently what atmospheric signatures would be expected if a Venus-like exoplanet were discovered.” Future satellites could then search for signs of a biosphere, the zone where organisms can live, on such planets. Scientists from the DLR Remote Sensing Technology Institute in Oberpfaffenhofen have been working with the researchers from the DLR Institute of Planetary Research in Berlin-Adlershof for some time in the search for what are known as ‘biomarkers’ – components in the atmosphere or on the surface of planets that have been created through the metabolic activity of life forms.

The intention is to make further use of the SCIAMACHY measurements in the ‘Planetary Evolution and Life’ Helmholtz Alliance. This international research network is investigating the question, among other things, as to what conditions must prevail on a planet in order for life to develop. Here, the data offer a realistic background for modelling the radiation transport in the atmospheres of Earth-like planets.

Additional measurements of spectra in various phases of Venus are planned with SCIAMACHY. In addition, studies are underway as to how the other bright planets of our solar system, Mars, Jupiter and Saturn, can also be used as extraterrestrial objects of investigation.

Venus – bright, small and “difficult to measure”

Relative positions of Earth and Venus, March and June 2009. Credit: DLR/NASA-JPL Solar System Simulator.

Venus, with its 12 100-kilometre diameter, is almost as large as our home planet.  Seen from Earth, it appears as the brightest celestial body after the Sun and Moon – but with a subtended angle of less than one minute of arc (one sixtieth of a degree) it looks relatively small. As a consequence, in order to keep this small ‘Venusian disc’ in SCIAMACHY’s field of view long enough to perform the observations, the instrument configuration had to be changed substantially. Due to the arrangement of SCIAMACHY’s observation windows, Venus only appears above Earth’s horizon briefly after rising – a process which is repeated 14 to 15 times per day as a result of Envisat’s orbit of the Earth. Precise planning as well as chronologically exact measurements finally enabled the derivation of Venus spectra on the basis of the solar radiation reflected and scattered by the planet’s atmosphere. Both in March and in June 2009 SCIAMACHY recorded Venus spectra during several orbits of Earth (see PDF download ‘SCIAMACHY spectra of Venus’ in the right column).

As an inner planet, Venus moves faster around the Sun than Earth. Therefore, the relative positions of Earth, Venus and Sun changed significantly between March and June 2009 (see image). In March 2009, Venus was close to what is known as its ‘inferior conjunction’, directly between Earth and the Sun. Seen from Earth, it presented mainly its dark side and only a thin crescent of the sunlit planetary disc was visible. At this time, the distance of Venus from Earth was only 43 million kilometres. In June 2009, by contrast, the Sun, Venus and Earth formed an almost right-angled triangle. Although the distance between Venus and Earth had grown to 127 million kilometres, more than 50 percent of Venus’ disc now lay in sunlight when seen from Earth.

SCIAMACHY on Envisat

ESA’s Envisat Earth observation satellite has been orbiting Earth since 2002 and supplies valuable information about the state of Earth. The SCIAMACHY atmospheric instrument on board Envisat, designed under the lead management of  DLR together with Dutch and Belgian partners, measures the solar radiation scattered back from Earth’s surface and atmosphere from the ultraviolet to the near-infrared parts of the spectrum. These measurements can be used to determine the atmospheric concentration of many different trace gases, which are important with regard to air quality, the greenhouse effect and ozone chemistry. SCIAMACHY is the first and currently the only satellite instrument in the world to carry out measurements of such complexity. The project is managed by DLR and the Netherlands Space Office (NSO). The Institute of Remote Sensing and Environmental Physics (IFE/IUP) of the University of Bremen is responsible for the scientific management the project.

German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR)

A new study conducted at Georgia Tech found that sandfish (shown here) place their limbs against their sides and create a wave motion with their bodies like snakes to swim through sand. (Georgia Tech Photo: Gary Meek)

“When started above the surface, the animals dive into the sand within a half second. Once below the surface, they no longer use their limbs for propulsion—instead, they move forward by propagating a traveling wave down their bodies like a snake,” said study leader Daniel Goldman, an assistant professor in Georgia Tech’s School of Physics.

With funding from the National Science Foundation and the Burroughs Wellcome Fund, the research team used high-speed X-ray imaging to visualize sandfish—formally called Scincus scincus —burrowing into and through sand. The team used that information to develop a physics model of the lizard’s locomotion.

The sandfish used in this study inhabits the Sahara desert in Africa and is approximately four inches long. It uses its long, wedge-shaped snout and countersunk lower jaw to rapidly bury into and swim within sand. The sandfish’s body has flattened sides and is covered with smooth shiny scales, its legs are short and sturdy with long and flattened fringed toes and its tail tapers to a fine point.

• Watch a video of a sandfish using its limbs to run on the surface and rapidly bury into the interior of granular media here.




• Watch a video of a sandfish slither like a snake through granular media here.




• Watch a video of a sandfish swim through granular media with opaque markers on its body that clearly show that its limbs are held close to its body during swimming here.

To conduct controlled experiments with the sandfish, Goldman and graduate students Ryan Maladen, Yang Ding and Chen Li built a seven-inch by eight-inch by four-inch-deep glass bead-filled container with tiny holes in the bottom through which air could be blown. The air pulses elevated the beads and caused them to settle into a loosely packed solid state. Repeated pulses of air compacted the material, allowing the researchers to closely control the density of the material.

Georgia Tech graduate student Ryan Maladen (left) and physics assistant professor Daniel Goldman set up the high-speed X-ray imaging system to record the movements of sandfish below the sand surface. (Georgia Tech Photo: Gary Meek)

Since a sandfish might encounter and need to move through different densities of sand in the desert, the researchers tested whether sandfish locomotion changed when burrowing through media with volume fractions of 58 and 62 percent—typical values for desert sand.

“Since loosely packed media is easier to push through and closely packed is harder to push through, we thought there should be some difference in the sandfish’s locomotion,” said Goldman. “But the results surprised us because the density of the granular media did not affect how the sandfish traveled through the sand; it was always the same undulatory wavelike pattern.”

For a given wave frequency, the swimming speed depended only on the frequency of the wave and not on the density. Unexpectedly though, the animals could swim a bit faster in closely packed material by using a higher frequency range. The team also varied the diameter of the glass beads, but still observed similar wavelike motion.

By tracking the sandfish in the X-ray images as it swam through the glass beads, Goldman was able to characterize the sandfish’s motion—called its kinematics—as the form of a single-period sinusoidal wave that traveled from the head to the tail.

“The large amplitude waves over the entire body are unlike the kinematics of other undulatory swimming organisms that are the same size as the sandfish, like eels, which propagate waves that start with a small amplitude that gets larger toward the tail,” explained Goldman.

After collecting the experimental data, Goldman’s team developed a physics model to predict the speed at which sandfish swim through sand. The model was inspired by the resistive force theory, which allowed the researchers to partition the body of the sandfish into segments, each of which generated thrust and experienced drag when moving through the granular environment.

“When you balance the thrust and drag, you get motion at some velocity, but we needed to determine the forces on the animal segments because we don’t have the appropriate equations for drag force during movement through granular media,” explained Goldman.

To establish these equations, the researchers measured the granular thrust and drag forces on a small stainless steel cylindrical rod, thus allowing them to predict the wave efficiency and optimal kinematics. They found that the faster the sandfish propagate the wave, the faster they move forward through granular media—up to speeds of six inches per second. This speed allows the animal to escape predators, the heat of the desert surface and quickly swim to ambush surface prey they detect from vibrations.

Georgia Tech researchers developed a physics model of sandfish locomotion through granular media. They found that media density did not affect the lizard’s motion—it was always the same snakelike movement. (Georgia Tech Photo: Gary Meek)

“The results demonstrate that burrowing and swimming in complex media like sand can have intricacy similar to that of movement in air or water, and that organisms can exploit the solid and fluid-like properties of these media to move effectively within them,” noted Goldman.

In addition to having a biological impact, this study’s results also have ecological significance, according to Goldman. Understanding the mechanics of subsurface movement could reveal how the actions of small burrowing organisms like worms, scorpions, snakes and lizards can transform landscapes by their burrowing actions. This research may also help engineers build sandfish-like robots that can travel through complex environments.

“If something nasty was buried in unconsolidated material, such as rubble, debris or sand, and you wanted to find it, you would need a device that could scamper on the surface, but also swim underneath the surface,” Goldman said. “Since our work aims to fundamentally understand how the best animals in nature move in these complex unstructured environments, it could be very valuable information for this type of research.”

This material is based upon work supported by the National Science Foundation (NSF) under Award No. PHY-0749991 and the Burroughs Wellcome Fund. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the researcher and do not necessarily reflect the views of the NSF.

Related Links

• Daniel Goldman
• Georgia Tech School of Physics

By Abby Vogel – Georgia Institute of Technology

A new prostate cancer “homing device” could improve detection and allow for the first targeted treatment of the disease.

This image depicts transporter molecules carrying therapeutic drugs to PSMA targets on a prostate cancer cell. A Purdue research team designed a molecule that finds and penetrates prostate cancer cells and can transport drugs or imaging agents into the cell. (Image courtesy of Low laboratory)

A team of Purdue University researchers has synthesized a molecule that finds and penetrates prostate cancer cells and has created imaging agents and therapeutic drugs that can link to the molecule and be carried with it as cargo.

A radioimaging application used for body scans is expected to enter clinical trials this fall, and an optical imaging application used to measure prostate cancer cells in blood samples is already in clinical trials.

Philip Low, the Ralph C. Corley Distinguished Professor of Biochemistry who led the team, said a targeted treatment could be much more effective in treating cancer and would greatly reduce the harmful side effects associated with current treatments.

“Currently none of the drugs available to treat prostate cancer are targeted, which means they go everywhere in the body as opposed to only the tumor, and so are quite toxic for the patient,” said Low, who is a member of the Purdue Cancer Center. “By being able to target only the cancer cells, we could eliminate toxic side effects of treatments. In addition, the ability to target only the cancer cells can greatly improve imaging of the cancer to diagnose the disease, determine if it has spread or is responding to treatment.”

Prostate cancer is the most common cancer, other than skin cancers, and is the second leading cause of cancer death in American men, according to the American Cancer Society. It is estimated that about 192,280 new cases will be diagnosed and 27,360 men will die of prostate cancer in the United States this year.

The molecule Low’s team created attaches to prostate-specific membrane antigen, or PSMA, a protein that is found on the membrane of more than 90 percent of all prostate cancers. It also is found on the blood vessels of most solid tumors and could provide a way to cut off the tumor blood supply, Low said.

“A lot of new drugs are being designed to destroy the vasculature of solid tumors, and, if they could be linked to this new targeting molecule, we could have a two-pronged attack for prostate cancer,” he said. “We could not only kill the prostate cancer cells directly, we could also destroy the vasculature that feeds the tumors.”

There also is potential for the targeting molecule to be used to attack the vasculature of solid tumors of other types of cancers, Low said.

Two papers detailing the work of the Purdue team were published in the June 1 issue of Molecular Pharmaceutics. Endocyte Inc. funded the work.

The team’s animal study data shows an ability to eliminate human prostate cancer cells in mice with no evidence of collateral toxicity in normal tissue.

Sumith Kularatne, a graduate student in Purdue’s chemistry department and first author of both papers, compared the targeting molecule to a homing device.

“The molecule acts like a homing device for prostate cancer,” he said. “PSMA, which is found only on prostate cancer cells and tumor blood vessels, acts as the homing signal that the molecule targets. The molecule and its cargo go only to cancerous tissue, leaving healthy tissue unharmed.”

Philip Low, the Ralph C. Corley Distinguished Professor of Biochemistry at Purdue, and graduate student Sumith Kularatne, in foreground, examine the uptake of an imaging agent in prostate cancer cells. Low led a research team that designed a molecule to find and penetrate prostate cancer cells and has created imaging agents and therapeutic drugs that can link to the molecule and be carried with it as cargo. (Purdue University photo/Andrew Hancock)

Once the molecule reaches the PSMA protein, it binds to it. The molecule is designed with a specific shape that fits with the protein like a key to a lock, Kularatne said. The molecule and its cargo are then carried inside the cell with the protein as it goes through its normal cycle.

In 1995 Low developed a similar method to infiltrate cancer cells by attaching treatments to the vitamin folate, which many cancers rapidly consume. This method provided a “Trojan Horse” entry of large treatment molecules that otherwise would not be able to enter cancer cells.

Low was inspired to find a similar way to target prostate cancer, which does not have the same appetite for folate, he said.

A clinical trial of the radioimaging application is expected to begin at the Indiana University Medical Center in the fall through a collaboration between the Purdue Cancer Center and the Indiana University Cancer Center with additional support from Endocyte Inc.

A radioimaging agent linked to the targeting molecule will be injected into prostate cancer patients and pictures will be taken using a special camera that detects radioactivity. The pictures show where the cancer is present to help doctors determine if it has metastasized, or spread, to any other areas of the body. It also will help doctors decide on the best course of treatment, Low said.

There is currently only one radioimaging agent for prostate cancer approved by the Food and Drug Administration.

“The current imaging capabilities available for prostate cancer are very poor,” Low said. “The existing imaging agent is limited because of its large size, which is difficult to get into a solid tumor. Also it seeks out a target located inside the cancer cell and is only able to mark injured cells that are falling apart as opposed to actively growing cancer cells.”

The targeting molecule and radioimaging agent combination designed by Low’s group is more than 150 times smaller than the existing agent and has much easier penetration through a solid tumor to reach all of the cells inside, he said. It also has the advantage of targeting an area of PSMA exposed on the outside of cancer cells.

Already in clinical trials is an optical imaging application that involves attaching a fluorescent dye to the targeting molecule and mixing it with a patient’s blood sample. Circulating prostate cancer cells in the sample fluoresce and are easily measured to help in diagnosing patients with prostate cancer. Researchers also are investigating whether this could be used to evaluate a patient’s response to therapy, Low said.

Low’s research group modeled the targeting molecule after a naturally occurring molecule that strongly binds to PSMA, called DUPA. Several alterations were necessary to create a molecule that fit the needs of a homing device and delivery vehicle, Kularatne said. The team created an area on the molecule that would link to various imaging or therapeutic agents to bring them along as cargo and created a spacer that would stretch the molecule so that its cargo would not keep it from properly fitting into the binding site. The spacer also was designed to improve binding of the targeting molecule to PSMA.

In addition to Low and Kularatne, co-authors of the papers include Endocyte researchers Kevin Wang and Hari-Krishna R. Santhapuram, graduate student in medicinal chemistry Zhigang Zhou, graduate student in chemistry Jun Yang, and professor of medicinal chemistry and molecular pharmacology Carol B. Post.

Low is the chief science officer for Endocyte, a Purdue Research Park-based company that develops receptor-targeted therapeutics for the treatment of cancer and autoimmune diseases. Endocyte holds the license to many of Low’s drug-targeting technologies.

Papers:

Prostate-Specific Membrane Antigen Targeted Imaging and Therapy of Prostate Cancer Using a PSMA Inhibitor as a Homing Ligand
Sumith A. Kularatne, Kevin Wang, Hari-Krishna R. Santhapuram, and Philip S. Low

Design, Synthesis, and Preclinical Evaluation of Prostate-Specific Membrane Antigen Targeted ^99mTc-Radioimaging Agents
Sumith A. Kularatne, Zhigang Zhou, Jun Yang, Carol B. Post, and Philip S. Low

By Elizabeth K. Gardner – Purdue University

Bridges of nanoparticles. These are held together by supramolecular forces. The researchers are able to accurately determine the three dimensions of the bridges. Source: Universiteit Twente

The Twente scientists have developed an entirely new method for building bridges of nanoparticles, using supramolecular forces: gravitational forces between various molecules. These forces cause the nanoparticles, which constitute the bridge, to fall automatically in the right place. This is called self-assembly. In building the bridges, the researchers use polystyrene spheres of around 500 nanometres in size (one nanometre is a millionth of a millimetre). They dissolve the spheres in water, and the solution is subsequently deposited into grooves on a surface. The solution evaporates, leaving behind a line of spheres in the groove. The researchers then add to this a ‘supramolecular glue’. This consists of two components: gold particles and so-called dendrimers. These particles adhere to each other and to the polystyrene particles and thus fix the structure. This creates a bar-shaped structure. The bar is then stamped on to a different surface. By stamping the bar on to a grooved surface, the bridge of nanoparticles is created.

Ingenious

The method devised by the scientists is ingenious: they are able to determine all the dimensions of the bridge accurately. The length of the grooves determines the length of the bridge, the breadth of the groove determines the breadth and the speed with which the line is filled determines the thickness (number of layers). In this case, the researchers built bridges of polystyrene and gold particles, but they can also use the method for other materials, such as silica.

According to researchers, we will eventually be able to apply the nano bridges in, among other things, the manufacture of optical filters that allow or disallow specific wave lengths to pass through. Another area of application is microelectronics, where we could use the bridges for minuscule links or sensors.

The research was carried out within the Molecular Nanofabrication Group of Prof. Jurriaan Huskens and the Materials Science and Technology of Polymers Group of Prof. Julius Vancso. Both groups are part of the MESA+ Institute for Nanotechnology at the University of Twente.

The article ‘Freestanding 3D Supramolecular Particle Bridges: Fabrication and Mechanical Behavior’ by Xing Yi Ling, In Yee Phang, Holger Schönherr, David Reinhoudt, Julius Vancso and Jurriaan Huskens is published in the 19 June issue of the leading specialist journal, Small. An image of the bridges is displayed on the cover of the publication. You can see a digital version of the article here.

Universiteit Twente (University of Twenty)

The CCD220 detector at the core of the OCam camera has 240 x 240 pixels and has a readout noise ten times smaller than detectors in current use, making it ideal for the faint light camera systems to be used on the second generation of Very Large Telescope instruments. It was developed by the British manufacturer e2v technologies. Source: ESO

“The performance of this breakthrough camera is without an equivalent anywhere in the world. The camera will enable great leaps forward in many areas of the study of the Universe,” says Norbert Hubin, head of the Adaptive Optics department at ESO. OCam will be part of the second-generation VLT instrument SPHERE. To be installed in 2011, SPHERE will take images of giant exoplanets orbiting nearby stars.

A fast camera such as this is needed as an essential component for the modern adaptive optics instruments used on the largest ground-based telescopes. Telescopes on the ground suffer from the blurring effect induced by atmospheric turbulence. This turbulence causes the stars to twinkle in a way that delights poets, but frustrates astronomers, since it blurs the finest details of the images.

Adaptive optics techniques overcome this major drawback, so that ground-based telescopes can produce images that are as sharp as if taken from space. Adaptive optics is based on real-time corrections computed from images obtained by a special camera working at very high speeds. Nowadays, this means many hundreds of times each second. The new generation instruments require these corrections to be done at an even higher rate, more than one thousand times a second, and this is where OCam is essential.

“The quality of the adaptive optics correction strongly depends on the speed of the camera and on its sensitivity,” says Philippe Feautrier from the LAOG, France, who coordinated the whole project. “But these are a priori contradictory requirements, as in general the faster a camera is, the less sensitive it is.” This is why cameras normally used for very high frame-rate movies require extremely powerful illumination, which is of course not an option for astronomical cameras.

OCam and its CCD220 detector, developed by the British manufacturer e2v technologies, solve this dilemma, by being not only the fastest available, but also very sensitive, making a significant jump in performance for such cameras. Because of imperfect operation of any physical electronic devices, a CCD camera suffers from so-called readout noise. OCam has a readout noise ten times smaller than the detectors currently used on the VLT, making it much more sensitive and able to take pictures of the faintest of sources.

OCam is the world’s fastest high precision faint light camera. Developed in Europe, the camera is highly sensitive and able to take 1500 images per second. OCam has been specially designed and built by a team of French engineers from LAM, LAOG and the OHP and uses the CCD220 detector developed by e2v technologies. The technology developed with OCam has been transferred to ESO for use with the second generation instruments of ESO’s Very Large Telescope. Source: ESO

“Thanks to this technology, all the new generation instruments of ESO’s Very Large Telescope will be able to produce the best possible images, with an unequalled sharpness,” declares Jean-Luc Gach, from the Laboratoire d’Astrophysique de Marseille, France, who led the team that built the camera.

“Plans are now underway to develop the adaptive optics detectors required for ESO’s planned 42-metre European Extremely Large Telescope, together with our research partners and the industry,” says Hubin.

Using sensitive detectors developed in the UK, with a control system developed in France, with German and Spanish participation, OCam is truly an outcome of a European collaboration that will be widely used and commercially produced.

More information

The three French laboratories involved are the Laboratoire d’Astrophysique de Marseille (LAM/INSU/CNRS, Université de Provence; Observatoire Astronomique de Marseille Provence), the Laboratoire d’Astrophysique de Grenoble (LAOG/INSU/CNRS, Université Joseph Fourier; Observatoire des Sciences de l’Univers de Grenoble), and the Observatoire de Haute Provence (OHP/INSU/CNRS; Observatoire Astronomique de Marseille Provence).

OCam and the CCD220 are the result of five years work, financed by the European commission, ESO and CNRS-INSU, within the OPTICON project of the 6th Research and Development Framework Programme of the European Union. The development of the CCD220, supervised by ESO, was undertaken by the British company e2v technologies, one of the world leaders in the manufacture of scientific detectors. The corresponding OPTICON activity was led by the Laboratoire d’Astrophysique de Grenoble, France. The OCam camera was built by a team of French engineers from the Laboratoire d’Astrophysique de Marseille, the Laboratoire d’Astrophysique de Grenoble and the Observatoire de Haute Provence. In order to secure the continuation of this successful project a new OPTICON project started in June 2009 as part of the 7th Research and Development Framework Programme of the European Union with the same partners, with the aim of developing a detector and camera with even more powerful functionality for use with an artificial laser star. This development is necessary to ensure the image quality of the future 42-metre European Extremely Large Telescope.

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

ESO European Organisation for Astronomical Research in the Southern Hemisphere

This color image is the highest resolution topography map to date of the moon's south pole. Credit: NASA

The map was created by scientists at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., who collected the data using the Deep Space Network’s Goldstone Solar System Radar located in California’s Mojave Desert. The map will help Lunar Crater Observation and Sensing Satellite (LCROSS) mission planners as they target for an encounter with a permanently dark crater near the lunar South Pole.

“Since the beginning of time, these lunar craters have been invisible to humanity,” said Barbara Wilson, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and manager of the study. “Now we can see detailed topography inside these craters down to 40 meters [132 feet] per pixel, with height accuracy of better than 5 meters [16 feet].”

The terrain map of the moon’s south pole is online at: http://www.nasa.gov/topics/moonmars/features/moon-20090618.html .

Scientists targeted the moon’s south polar region using Goldstone’s 70-meter (230-foot) radar dish. The antenna, three-quarters the size of a football field, sent a 500-kilowatt-strong, 90-minute-long radar stream 373,046 kilometers (231,800 miles) to the moon. Signals were reflected back from the rough-hewn lunar terrain and detected by two of Goldstone’s 34-meter (112-foot) antennas on Earth. The roundtrip time, from the antenna to the moon and back, was about two-and-a-half seconds.

The scientists compared their data with laser altimeter data recently released by the Japanese Aerospace Exploration Agency’s Kaguya mission to position and orient the radar images and maps. The new map provides contiguous topographic detail over a region approximately 500 kilometers (311 miles) by 400 kilometers (249 miles).

Funding for the program was provided by NASA’s Exploration Systems Mission Directorate. JPL manages the Goldstone Solar System Radar and the Deep Space Network for NASA. JPL is managed for NASA by the California Institute of Technology in Pasadena.

More information about the Goldstone Solar System Radar and Deep Space Network is at http://deepspace.jpl.nasa.gov/dsn . More information about NASA’s exploration program to return humans to the moon is at http://www.nasa.gov/exploration .

NASA Jet Propulsion Laboratory

Researchers at the Max Planck Institute for Chemical Ecology in Jena and their colleagues from the Czech Academy of Sciences in Prague have developed a new method to quickly and reliably detect metabolites, such as sugars, fatty acids, amino acids and other organic substances from plant or animal tissue samples. One drop of blood – less than one micro liter – is sufficient to identify certain blood related metabolites. The new technique, called MAILD, is based on classical mass spectrometry (MALDI-TOF/MS) and enables researchers to measure a large number of metabolites in biological samples, opening doors for targeted and high-throughput metabolomics. Because of its versatile applications, also in medical diagnostics, the invention is protected by patent. (Proc. Natl. Acad. Sci. USA, Early Edition, June 2009).

One drop of blood is sufficient for detailed metabolomic analysis by MAILD mass spectrometry. Image: MPI for Chemical Ecology, Aleš Svatoš

Mass spectrometry is an analytical technique used to elucidate the molecular composition and structure of chemical compounds. In the last two decades mass spectrometry found vast applications in biology, especially for analyzing of large biomolecules. Matrix-Assisted Laser Desorption/Ionization (MALDI), wherein bio-molecules (e.g. proteins) are co-crystallized with a chemical substance called a matrix subsequently irradiated with a laser leads to the formation of protein ions which can be analyzed and detected.

However, matrices used in the MALDI technique have a substantial disadvantage: the laser beam not only forms ions from the substances of interest; it also forms low-mass ions (less than 500 Da) originating from the matrix. “Because of these small interfering ions we were not able to analyze small molecules that play crucial roles in the metabolism of organisms,” explains Aleš Svatoš, head of the mass spectrometry/proteomics research group at the Max Planck Institute. “The ions that originated from conventional matrices were like a haystack in which we wanted to find a few and important needles.” Therefore the MALDI technique found only limited application in the field of “metabolomics”.

Instead of improving the search for the “needles”, i.e. metabolites such as sugars, fatty acids, amino acids, and other organic acids, the scientists began to alter the matrices with which the samples were applied so that no more interfering matrix-related ions were generated. In other words: they tried to remove the haystack to make the needles visible. The researchers succeeded with the help of physical and organic chemistry, based on the Brønsted-Lowry acid-base theory, and formulated conditions for rational selection of matrices that did not generate interfering ions but provided rich mass spectra of particular kinds of metabolites in real samples.

With the new experimental protocols they called “Matrix-Assisted Ionization/Laser Desorption – MAILD”, the scientists were able to quickly and reliably determine more than 100 different analytes from single and small-sized samples. “The analysis of a very small plant leaf sample from Arabidopsis thaliana, in fact a circle area with a radius of just about 0.5 millimeter, revealed over a hundred analyte peaks, among which 46 metabolites could be identified. Interestingly, among them were eight of a total of eleven intermediates of the citric acid cycle, which is vital for most organisms,” says Rohit Shroff, a native of India, who was a PhD student at the “International Max Planck Research School” and conducted the experiments.

The new MAILD method allows measurements from diverse biological and medical materials. Apart from plant and insect samples the scientists also studied a clinical sample: they were able to determine a wide range of blood-specific organic acids in one drop of human blood, smaller than a micro liter. In medical diagnostics such measurements are still conducted with intricate methods. If the scientists succeed in not only identifying, but also quantifying the metabolites, MAILD could develop into a fast method for medical and biological diagnostics.

Original work:

Rohit Shroff, Lubomír Rulíšek, Jan Doubský, Aleš Svatoš
Acid-base-driven matrix-assisted mass spectrometry for targeted metabolomics
Proceedings of the National Academy of Sciences USA, Early Edition, June 2009, doi: 10.1073/pnas.0900914106

Max Planck Society

Between a polycrystalline material’s grains (saffron layers) exist disorderly areas called grain boundaries, the behavior of which has been difficult to understand. The green and blue objects in the boundary are string-like collections of atoms that NIST scientists have recently shown behave like glass-forming liquids, a similarity that should help scientists analyze a wide range of materials. Credit: NIST.

Most metals and ceramics used in manufacturing are polycrystals. The steel in a bridge girder is formed from innumerable tiny metal crystals that grew together in a patchwork as the molten steel cooled and solidified. Each crystal, or “grain,” is highly ordered on the inside, but in the thin boundaries it shares with the grains around it, the molecules are quite disorderly. Because grain boundaries profoundly affect the mechanical and electrical properties of polycrystalline materials, engineers would like a better understanding of grain boundaries’ formation and behavior. Unfortunately, grain boundary formation in most technically useful alloys has eluded efforts to observe it for a century.

“You’d like to have simple engineering rules regarding how a material’s going to break,” says NIST materials scientist Jack Douglas. “For example, corrosion typically travels along grain boundaries, so polycrystals usually fracture along them. But metals melt and deform at very high temperatures, so observing them under those conditions is a challenge.”

While some scientists had speculated that the molecules in grain boundaries behave similarly to the way molecules do in glass-forming liquids, whose properties are well understood, none had found conclusive evidence to back up such a claim. That started to change when NIST theorist James Warren saw a conference presentation by the University of Alberta’s Hao Zhang concerning some odd “strings” of atoms in his simulation of grain boundary motion using a simulation technique called molecular dynamics. The collective atomic behavior observed in grain boundaries reminded the team of prior findings made at NIST about glass-forming liquids, whose atoms also form strings.

Subsequently, the team showed that the strings of atoms arising in grain boundaries are strikingly similar in form, distribution and temperature dependence to the string-like collective atomic motions generally found in glass-forming liquids—and that properties for both types of substances change with temperature in virtually the same way. “This work represents a paradigm shift in our understanding of grain boundaries,” Douglas says. “All the important qualities relating to atomic motion in both of these types of materials—the development of these string-like atomic motions, or the amplitude at which their atoms rattle—are strikingly similar. For all intents and purposes, grain boundaries are a type of glass.”

Douglas says the findings could permit substantial progress in predicting the failure of many materials important in construction and manufacturing and could improve our understanding of how crystals form boundaries with one another.

* H. Zhang, D.J. Srolovitz, J.F. Douglas and J.A. Warren. Grain boundaries exhibit the dynamics of glass-forming liquids. Proceedings of the National Academy of Sciences. Vol.106, No. 10 (2009).

National Institute of Standards and Technology (NIST)