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Rise of the molecular machines

Rise of the molecular machines

Chemists are putting molecules to work in ways only limited by our imagination 

Josh Howgego

Our bodies are full of molecular machines and their synthetic counterparts may soon be all around us too © SCIENCE PHOTO LIBRARY

As I extend an arm to pick up my cup of coffee there is an army of miniature machines operating inside my bicep. But what is it that makes the biomolecules in a muscle organise themselves into a powerful instrument, whilst the collections of atoms swilling around inside my cup are inanimate?

Nuts and bolts 

Mastering and mimicking how molecular machines work has been a fascinating adventure for chemists, and one in which their creativity has been unleashed. The parts that make up the tiny world of molecular machines are described using familiar terms: an alkyl chain might be called a piston, for example, or a benzene ring a wheel. But before these tiny machines could be built, an in depth knowledge of how to hold the component pieces together was needed.

Instead of nuts and bolts, molecular machines are held together by intermolecular forces; the subtle electrostatic attractions and repulsions between molecules. Chemistry is inherently dynamic, so these forces can hold molecules together strongly, but also enforce softer attractions, which pull molecules together, but still allow some degree of movement (see table.¹ And it is these softer interactions that are key to many molecular machines. 

Intermolecular forces explained. Download the pdf at the end of the article to see a high resolution version of this image.

Indeed one of the main steps towards the first molecular machine was working out how to mechanically interlock two molecules, whilst still allowing them freedom to move; a bit like having a ring slide along a piece of string. This problem was pondered for a long time, until the 1990s when several developments converged and made it possible.  

A molecular shuttle 

Fraser Stoddart, a chemist at Northwestern University, US, produced one of the early prototype molecular machines in 1994 (fig?1).² The machine has a track with two stations and a shuttle that can slide along between them. The shuttle can't escape from the end of the track because there are bulky stopper groups at both ends which it can't fit over. 

Fig 1 - The key parts of Stoddart's molecular shuttle are the two stations (blue), the shuttle (orange) and the bulky stoppers (green)

The intermolecular forces that exist between the shuttle and the different points on the track determine where it sits. Because the shuttle is made from non-polar, aromatic building blocks, the - stacking intermolecular forces between it and the aromatic ring-based stations are quite strong. The forces between the shuttle and the track made of polyether chains are much weaker, as there are no aromatic moieties to stack against. 

Under normal conditions the shuttle doesn't have much preference between the two stations, so it is free to move rapidly over the polyether chain and between the two ports. However, the machine is cleverly designed to change its properties under different conditions. The nitrogen atoms in the first station are basic. That is, they are easily able to accept a hydrogen ion (proton) on exposure to acid. In the process the first station gains a positive charge. This repels the shuttle (which also has a positive charge), and so the shuttle is pushed to the second station. 

What the chemists had made was essentially a switch. With the addition of a little acid, their machine switched from freely moving between both states to being confined at a single station. 

Molecular muscles 

Fig 2 - The actin and myosin filaments in muscles use protein-based machines to pull past each other

It is hoped that machines like Stoddart's will eventually function like the actin and myosin filaments that drive arms and legs (fig?2). Myosin fibre has protein-based molecular machines which skull along the surface of actin like a rowing boat gliding over water. Molecular machines might one day act as artificial muscles, powering robots or prosthetic limbs. 

The ability to emulate the molecular machines which power logistics operations in living systems is also desirable. Before mitosis, chromosomes need to be copied, and then each set must be transported to opposite ends of their cell. The biological solution is a network of microscopic fibres called microtubules strung across a cell's diameter, and kinesin (a motor protein) that can move along these rails. The kinesin hitches up its chromosone cargo, and hauls it across the cell.

But so far molecular machines have been employed most successfully as information storage media (the 'freely moving' and 'stuck' modes of the shuttle can be interpreted as a digital readout: off or on; 0 or 1). In contrast, the challenge of making artificial muscles or kinesin mimics is hard because one molecular machine on its own is too weak to be useful. Transferring controlled motion from a single interlocked molecule to a complex system - where lots of shuttles work together - has proved difficult.

Some prototype molecular machines have been developed, however, which - although drastically simplified - work similarly to the actin and myosin in muscles. But these don't use intermolecular forces in the same way as Stoddart's shuttle. One model machine, developed by chemist David Leigh, at the University of Edinburgh, UK, instead works by sequentially making and breaking different types of covalent chemical bonds.³

Fig 3 - Leigh's molecular walker can take steps along a pathway of alternating functional groups

The first part of the design is a walker (red in fig?3), with two different functional groups at either end: one thiol (-SH) and one amide (-CONH). The walker unit is connected to a track of benzene rings, each topped with either a thiol (the blue units), or an aldehyde (the green ones).  

Like Stoddart's machine, the impetus for the walker's motion comes from varying the nature of the solution surrounding the molecules from acidic to basic. To start the walker off, Leigh uses acidic conditions. This fixes the disulfide (S-S) linkage in place, but means the imide (N-N) bond is under equilibrium; it is constantly breaking and re-forming. When the imine bond is broken, the walker can pivot on its disulfide foot, and the imine foot is free to either re-form the bond with foothold 1  or move forwards to form a new bond with the aldehyde moiety at foothold 3  . (Importantly, the walker unit must be attached by at least one 'foot' at all times. It couldn't run or jump, as with both linkages broken the walker would drift off into solution). 

By increasing the pH of the solution, the walker is switched from having its disulfide foot fixed to the track to having the imine foot held down. The basic conditions mean that the disulphide bond is under equilibrium this time, and now it can move around. 

Nature generally uses non-covalent interactions to stick the feet of its protein machines to their tracks. So although Leigh's model walker is not strictly biomimetic, it is an ingeniously simple way of achieving
much the same outcome as cellular transporting machines. 

In the future, walkers operating on extended tracks could be made. And in theory it should be possible to attach cargo to a walker. This would make an excellent analogue of the chromosone-transporting kinesin protein. 

Making nanocars 

Fig 4 - Feringa's molecular rotor is powered by electrons, which excite the double bond and induce an E/Z-isomerisation

As Leigh's molecular walker demonstrates, it is often easier to use covalently bonded molecules to make molecular machines. Despite how well non-covalent forces are understood in theory, it remains challenging and fiddly to deploy them in real, working examples. 

Perhaps that is why Ben Feringa, a chemist working at the University of Groningen in the Netherlands, also steered clear of them. His interest lay in making machines that produce rotary, rather than linear, motion. His rotary motor (fig 4) is composed of a single part, allowing him to avoid sticking axles and levers together using intermolecular forces. 

Feringa recently combined four of his rotary motors with a chassis to develop what he called a four-wheeled molecule (but everyone else likes to call a nanocar).⁴ In order for the car to drive along a surface, the paddle-like rotors must turn. The surface the car travels along is a metal, with electricity running through it. The electrons excite the rotor's double bond and induce an E/Z  -isomerisation. The steric strain then leads to a helix inversion, and the molecule flips over, producing rotational motion and powering the car forwards (fig?5). 

Fig 5 - If the four rotors work in unison, the nanocar begins to drive along the surface

Today, molecular machines that can perform an increasingly varied range of tasks are still being constructed. Chemists have succeeded in replicating the sorts of machines nature uses in our bodies with artificial systems in single interlocked systems. These machines are truly biomimetic: they operate using the same principles that nature has used since its inception. Impressive, given that it took many millennia for them to evolve in the first place. 

The Nobel prize winning scientist Richard Feynman talked about molecular machines in 1959, when people had just begun to imagine what they might be like. 'What would be the utility of such machines?' he said. 'Who knows? I cannot see exactly what would happen, but I can hardly doubt that when we have some control over the arrangement of things on a molecular scale we will get an enormously greater range of possible properties that substances can have, and of the different things we can do.' 

What exactly the legacy of molecular machines will be still remains to be seen, but with molecular shuttles and nanocars already behind us, we can safely agree with Feynman that the possibilities are exciting. 

Josh Howgego is a science writer and chemistry PhD student based in Bristol, UK 

References

1 Bond strengths are taken from: J W Steed and J L Atwood, Supramolecular chemistry,  Wiley, 2000; M Nishio et al, CrystEngComm., 2009, 11, 1757 (DOI:10.1039/b902318f)
2 R A Bissell et al, Nature, 1994, 369, 133 (DOI:?10.1038/369133a0)
3 M von Delius, E M Geertsema and D A Leigh, Nat. Chem., 2010, 2, 96 (DOI:?10.1038/nchem.481)
4  T Kudernac et al, Nature, 2011, 479, 208 (DOI:?10.1038/nature10587) 

Measurements Hint Why the Universe Is Dominated by Matter, Not Anti-Matter

Dec. 26, 2012 — A collaboration with major participation by physicists at the University of Wisconsin-Madison has made a precise measurement of elusive, nearly massless particles, and obtained a crucial hint as to why the universe is dominated by matter, not by its close relative, anti-matter.

A pool holding four anti-neutrino detectors begins filling with ultra-pure water in September, 2012 at the Daya Bay Neutrino experiment. The experiment, just recognized by Science magazine as a breakthrough of the year, is helping to explain why the universe contains virtually no anti-matter. University of Wisconsin-Madison physicist Karsten Heeger and Physical Sciences Laboratory engineer Jeff Cherwinka both played major roles at the experiment. (Credit: Roy Kaltschmidt, Lawrence Berkeley National Laboratory)

The particles, called anti-neutrinos, were detected at the underground Daya Bay experiment, located near a nuclear reactor in China, 55 kilometers north of Hong Kong. For the measurement of anti-neutrinos it made in 2012, the Daya Bay collaboration has been named runner-up for breakthrough of the year from Science magazine.

Anti-particles are almost identical twins of sub-atomic particles (electrons, protons and neutrons) that make up our world. When an electron encounters an anti-electron, for example, both are annihilated in a burst of energy. Failure to see these bursts in the universe tells physicists that anti-matter is vanishingly rare, and that matter rules the roost in today's universe.

"At the beginning of time, in the Big Bang, a soup of particles and anti-particles was created, but somehow an imbalance came about," says Karsten Heeger, a professor of physics at UW-Madison. "All the studies that have been done have not found enough difference between particles and anti-particles to explain the dominance of matter over anti-matter."

But the neutrino, an extremely abundant but almost massless particle, may have the right properties, and may even be its own anti-particle, Heeger says. "And that's why physicists have put their last hope on the neutrino to explain the absence of anti-matter in the universe."

Heeger and his group at UW-Madison have been responsible for much of the design and development of the anti-neutrino detectors at Daya Bay. Jeff Cherwinka, from the university's Physical Sciences Laboratory in Stoughton, Wis. is chief engineer of the experiment and has overseen much of the detector assembly and installation. The construction of the experiment was completed this fall and data-taking started in October using the full set of anti-neutrino detectors.

Reactors, Heeger says, are a fertile source of anti-neutrinos, and measuring how they change during their short flights from the reactor to the detector, gives a basis for calculating a quantity called the "mixing angle," the probability of transformation from one flavor into another.

The measurement of the Daya Bay experiment, released in March 2012, even before the last set of detectors was installed, showed a surprisingly large angle, Heeger says. "People thought the angle might be really tiny, so we built an experiment that was 10 times as sensitive as we ended up needing.

"The neutrino community has been waiting for a long time for this parameter, which will be used for planning experiments for next decade and beyond," says Heeger, "and that is why it was recognized by Science."

As expected, Science's breakthrough of the year was the detection of the Higgs boson, an elusive sub-atomic particle that completes the "particle zoo" predicted by the standard model of physics. That discovery also had major participation by physicists from the UW-Madison.

source:sciencedaily.

Metallic Glass For Bone Surgery

Sep. 29, 2009 — It is possible that broken bones will in the near future be fixed using metallic glass. Materials researchers at ETH Zurich have developed an alloy that could herald a new generation of biodegradable bone implants.

Arc melter in which a plasma of up to 3000°C is produced between a tungsten tip (center) and a water-cooled copper plate. (Credit: ETH Zurich/LMPT)

When bones break, surgeons need screws and metal plates to fix the broken bones in place. These supports are usually made of stainless steel or titanium. Once the bones have healed, the metal parts have to be removed from the body via further surgery. In order to reduce the burden on patients, materials re-searchers have taken up the task of producing implants from bioabsorbable metals. These implants should stabilize the bones only for as long as they need to heal. The metal dissolves in the body over time, rendering removal surgery unnecessary. Implants made of magnesium-based alloys are proving particularly promising. Magnesium is mechanically stable and degrades completely by releasing ions which are tolerated by the body. However, all magnesium alloys have one major drawback: when they dissolve they produce hydrogen (H₂), which can be harmful to the body. Around the magnesium implants gas bubbles develop which hinder bone growth and thus the healing process, and potentially cause infection.

No side effects thanks to more zinc

Materials researchers working with Jörg Löffler, Professor of Metal Physics and Technology at ETH Zurich, have now eliminated these side-effects. They have succeeded in producing an innovative magnesium-zinc-calcium alloy in the form of a metallic glass which is biocompatible and shows significantly more favourable degradation behaviour. Metallic glasses are produced by rapid cooling of the molten material. The speed of the cooling process prevents the atoms from adopting the crystal structure found in traditional metals. As a result, metallic glasses have an amorphous structure like that of window glass. Thanks to this procedure, the researchers can add much more zinc to the molten magnesium than is possible with conventional alloys.

The glassy alloy developed by the ETH researchers Bruno Zberg, Peter Uggo-witzer and Jörg Löffler contains up to 35% zinc and 5% calcium atoms, with the rest made up of magnesium. A crystalline magnesium-zinc alloy can contain a maximum of 2.4% zinc atoms. If the percentage is higher, an undesired crystalline phase precipitates in the magnesium matrix. The magnesium-zinc-calcium glass can be produced in a thickness of up to 5 millimetres. The major advantage of a high percentage of zinc is that it changes the corrosion behaviour of the magnesium fundamentally. In fact, clinical tests with small platelets of the new magnesium-zinc-calcium alloy showed no hydrogen evolution! Thus this new alloy, in the form of a metallic glass, has considerable potential as a non-harmful bone implant material. The research work has been published in the online version of Nature Materials.

source:sciencedaily.

New funding to research graphene exceptionally thin, strong and a conductor of heat and electricity.

New funding to research graphene exceptionally thin, strong and a conductor of heat and electricity.

New funding to research graphene exceptionally thin, strong and a conductor of heat and electricity

New funding to research 'super material' graphene - Imperial scientists will receive £4.5 million public funds to investigate how 'super material' graphene can drive improvements in high-tech industry

Scientists at Imperial College London are set to receive over £4.5 million of public funding to investigate how the 'super material' graphene can drive improvements in high-tech industries, such as aerospace design and medical technologies.

The Chancellor of the Exchequer, George Osborne MP, today announced £21.5 million of capital investment to commercialise graphene, one of the thinnest, lightest, strongest and most conductive materials to have been discovered, marked by the 2010 Nobel Prize in Physics as one of the world’s most ground breaking scientific achievements.

Three research projects at Imperial will share the Engineering and Physical Sciences Research Council (EPSRC) funding as part of a new programme with a number of industrial partners, including aeroplane manufacturer Airbus. The scientists receiving the grant hope to develop graphene technologies that will contribute to the UK economy and can be applied by industries around the world.

Professor Neil Alford, deputy principal for research in Imperial's Faculty of Engineering, who is playing a key role in one of the new projects, said: "This is a tremendous opportunity for UK science and industry. The new funding will enable us to bring graphene a step closer to useful applications, by helping us explore the physical and mechanical properties of this remarkable material, as well as its behaviour at high frequency." In one project worth £1.35 million, led by Professor Tony Kinloch from the Department of Mechanical Engineering with colleagues from the Departments of Chemistry and Chemical Engineering, researchers will explore how combining graphene with current materials can improve the properties of aeroplane parts, such as making them resistant to lightning-strikes.They hope the same technology can also be used to develop coatings for wind-turbine blades, to make them scratch resistant and physically tougher in extreme weather conditions.

Professor Eduardo Saiz, from the Department of Materials, will develop new manufacturing processes using liquids that contain tiny suspended particles of graphene, in order to reduce the cost of currently expensive industrial techniques. This project will receive £1.91 million funding and involves scientists from Imperial’s Departments of Chemistry and Chemical Engineering, and Queen Mary, University of London.

£1.37 million of funding received by Professor Norbert Klein, also from the Department of Materials and shared with Imperial’s Department of Physics, will pay for new equipment to deposit extremely thin sheets of graphene, so scientists can explore its electrical properties. They hope that new medical scanning technology may be developed as a result of how graphene responds to high frequency electromagnetic waves, from microwave to terahertz frequencies and all the way to the wavelengths of visible light.

Professor Alford said: "At Imperial we will use the funding to build on first class research that crosses several College departments to vastly improve current technologies such as catalysis, supercapacitors, membranes, multifunctional polymer and ceramic composites and a whole range of applications at microwave and optical frequencies. We will work on improving the mechanical properties of composite materials, and addressing the electrical properties of devices, to develop exceptionally sensitive sensors for a range of applications in environmental monitoring and the medical sciences.

source:nanotechnologytoday

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WISHES YOU A VERY HAPPY NEW YEAR


"CHANGE IS COMPULSARY FOR ALL TO SUCCEED"

American mathematicians solve Ramanujan’s “deathbed” puzzle

“Ramanujan's legacy is much more important than anything anyone would have guessed”

American researchers claim to have solved a cryptic formula that renowned mathematician Srinivasa Ramanujan believed came to him in dreams while on his deathbed, the Daily Mailreported on Saturday.

The formula was contained in a letter he wrote to his mentor, the English mathematician G.H. Hardy, from his deathbed in 1920 outlining several new mathematical functions that had never been heard of before, together with a theory about how they worked. It had baffled mathematicians for more than 90 years, but new findings — presented at a conference at the University of Florida last month — reportedly show that Ramanujan’s “hunch” about his formula was right — that it could explain the behaviour of black holes.

“We've solved the problems from his last mysterious letters,” said the well-known American mathematician Ken Ono of Emory University.

“For people who work in this area of math, the problem has been open for 90 years … Ramanujan's legacy, it turns out, is much more important than anything anyone would have guessed when Ramanujan died.”

He said the so-called “deathbed puzzle” which, according to Ramanujan, was revealed to him by the goddess Namagiri, may unlock secrets about black holes. “We proved that Ramanujan was right. We found the formula explaining one of the visions that he believed came from his goddess. No one was talking about black holes back in the 1920s when Ramanujan first came up with mock modular forms, and yet, his work may unlock secrets about them,” said Professor Ono.

The Mail said that Ramanujan’s letter described several new functions that behaved differently from known theta functions, or modular forms, and yet closely mimicked them.

“Functions are equations that can be drawn as graphs on an axis, like a sine wave, and produce an output when computed for any chosen input or value. Ramanujan conjectured that his mock modular forms corresponded to the ordinary modular forms earlier identified by Carl Jacobi, and that both would wind up with similar outputs for roots of 1,” it said. Nobody at the time understood what the Indian mathematical genius was talking about.

“It wasn’t until 2002, through the work of Sander Zwegers, that we had a description of the functions that Ramanujan was writing about in 1920,” Prof. Ono said.

His team, which used modern mathematical tools to solve the puzzle, was “stunned” to find the function could be used even today.

source:the hindu

Nanotechnology? What's That?!

Nanotechnology? What's That?!
Engineers Create Exhibits on Achievements, Promise

Nanotechnology has already brought advances such as self-cleaning windows and energy-efficient LED lighting, and could soon deliver medical breakthroughs. To educate the public about nanotechnology's promise, the National Science Foundation has slated $20 million to fund a network of interactive exhibits at 100 museums around the country. 

MADISON, Wis.--Nanotechnology is the big buzz word in the world of science. It's going to impact just about everything we do, touch and see. And this next big thing is extraordinarily small.
You've heard the word, but do you know what nanotechnology is?
University of Wisconsin-Madison engineer Wendy Crone is on a mission. She and her interns are creating user-friendly exhibits to teach the public about the nanoworld.
"Nanotechnology is already starting to affect our lives, and it's anticipated that over the next 20 years it's going to have major impact on everything around us," Crone tells DBIS.
Nanotechnology means working at the scale of molecules. Crone's exhibits show just how small that scale is. "When you put nano in front of meter that means that's a billionth of a meter. So that means that you can fit 1 billion nanometers in one meter," she says. You'd have to slice one hair into 50,000 distinct strands to get a strand one-nanometer thick.
Nanotechnology is the secret behind how self-cleaning windows work and why LEDs are so energy-efficient.
"I think that nanotechnology, I mean, everyone continues to talk about it, is the next big thing," says intern Anne Vedder.
It might even save your life. Drug-coated nanoparticles will soon precisely deliver therapy to organs and tumors. Crone says it's going to be everywhere, and you probably won't even know that it's inside the products that you're using.
The National Science Foundation is giving $20 million to fund the national Nanoscale Informal Science Education Network (NISE Network), which will develop interactive exhibits to teach the public about nanotechnology. The network's goal is to have these exhibits in 100 museums across the United States in the next five years.

BACKGROUND: The engineering faculty, staff and students at the University of Wisconsin, Madison, are working with some of the nation's top science museums to create hands-on exhibits about nanotechnology. The effort is part of the $20 million Nanoscale Informal Science Education Network, which aims to develop innovative materials and vehicles to increase the public's knowledge and understanding of nanotechnology through exhibits.
ABOUT NANOTECHNOLOGY: Nanotechnology is science at the size of individual atoms and molecules: objects and devices measuring mere billionths of a meter, smaller than a red blood cell. At that size scale, materials have different chemical and physical properties than those of the same materials in bulk, because quantum mechanics is more important. For example, carbon atoms can conduct electricity and are stronger than steel when woven into hollow microscopic threads. Nanoparticles are already widely used in certain commercial consumer products, such as suntan lotions, "age-defying" make-up, and self-cleaning windows that shed dirt when it rains. One company manufactures a nanocrystal wound dressing with built-in antibiotic and anti-inflammatory properties. On the horizon is toothpaste that coats, protects and repairs damaged enamel, as well as self-cleaning shoes that never need polishing. Nanoparticles are also used as additives in building materials to strengthen the walls of any given structure, and to create tough, durable, yet lightweight fabrics.
SIZING THINGS UP: The tiny size scale makes it a challenge to translate nanotech research into something museum visitors can see, touch and comprehend, especially in an interactive format. UW-Madison already has the Nanoworld Discovery Center, which does just that. Among the exhibit's features is a segment about ferrofluids: tiny magnetic particles that flow like a liquid. They are used to damp vibrations and eliminate excess energy in expensive stereo systems. Visitors also learn about such applications as stain-resistant clothing, as well as compare incandescent bulbs to light-emitting diodes to learn how nanomaterials can help conserve energy.
source:sciencedaily.

From Super to Ultra: Just How Big Can Black Holes Get?

Dec. 18, 2012 — Some of the biggest black holes in the Universe may actually be even bigger than previously thought, according to a study using data from NASA's Chandra X-ray Observatory.

The black hole at the center of this galaxy is part of a survey of 18 of the biggest known black holes in the universe. This large elliptical galaxy is in the center of the galaxy cluster PKS 0745-19, which is shown in this composite image containing X-rays from Chandra (purple) and optical data from Hubble (yellow). Researchers found that some of the black holes in the survey may be about ten times more massive than previously thought. This includes ten that could weigh between 10 and 40 billion times the mass of the sun, making them "ultramassive" black holes. (Credit: X-ray: NASA/CXC/Stanford/Hlavacek-Larrondo, J. et al; Optical: NASA/STScI; Radio: NSF/NRAO/VLA)

Astronomers have long known about the class of the largest black holes, which they call "supermassive" black holes. Typically, these black holes have masses ranging between a few million and a few billion times that of our sun.
This new analysis of the brightest galaxies in a sample of 18 galaxy clusters suggests that the masses of at least ten of the supermassive black holes in these galaxies are ultramassive, in that they weigh between 10 and 40 billion times the mass of the sun. Astronomers refer to black holes of this size as "ultramassive" black holes and only know of a few confirmed examples.
"Our results show that there may be many more ultramassive black holes in the universe than previously thought," said study leader Julie Hlavacek-Larrondo of Stanford University and formerly of Cambridge University in the UK.
The researchers estimated the masses of the black holes in the sample by using an established relationship between masses of black holes, and the amount of X-rays and radio waves they generate. This relationship, called the fundamental plane of black hole activity, fits the data on black holes with masses ranging from 10 solar masses to a billion solar masses.
The black hole masses derived by Hlavacek-Larrondo and her colleagues were about ten times larger than those derived from standard relationships between black hole mass and the properties of their host galaxy. One of these relationships involves a correlation between the black hole mass and the infrared luminosity of the central region, or bulge, of the galaxy.
"These results may mean we don't really understand how the very biggest black holes coexist with their host galaxies," said co-author Andrew Fabian of Cambridge University. "It looks like the behavior of these huge black holes has to differ from that of their less massive cousins in an important way."
All of the potential ultramassive black holes found in this study lie in galaxies at the centers of massive galaxy clusters containing huge amounts of hot gas. Outbursts powered by the central black holes are needed to prevent this hot gas from cooling and forming enormous numbers of stars. To power the outbursts, the black holes must swallow large amounts of mass in the form of hot gas. Because the largest black holes can swallow the most mass and power the biggest outbursts, ultramassive black holes had already been predicted to exist to explain some of the most powerful outbursts seen. The extreme environment experienced by these galaxies may explain why the standard relations for estimating black hole masses do not apply.
These results can only be confirmed by making detailed mass estimates of the black holes in this sample, which is by modeling the motion of stars or gas in the vicinity of the black holes. Such a study has been carried out for the black hole in the center of the galaxy M87, the central galaxy in the Virgo Cluster, the nearest galaxy cluster to Earth. The mass of M87's black hole, as estimated from the motion of the stars, is significantly higher than the estimate using infrared data, approximately matching the correction in black hole mass estimated by the authors of the Chandra study.
"Our next step is to measure the mass of these monster black holes in a similar way to M87, and confirm their existence. I wouldn't be surprised if we end up finding the biggest black holes in the Universe," said Hlavacek-Larrondo. "If our results are confirmed, they will have important ramifications for understanding the formation and evolution of black holes across cosmic time."
In addition to the X-rays from Chandra, the new study also uses radio data from the NSF's Karl G. Jansky Very Large Array (JVLA) and the Australia Telescope Compact Array (ATCA) and infrared data from the 2 Micron All-Sky Survey (2MASS).
These results were published in the July 2012 issue of The Monthly Notices of the Royal Astronomical Society.
NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.
source:sciencedaily.
 

A Giant Puzzle With Billions of Pieces

Dec. 21, 2012 — Day after day, legions of microorganisms work to produce energy from waste in biogas plants. Researchers from Bielefeld University's Center for Biotechnology (CeBiTec) are taking a close look to find out which microbes do the best job. They are analysing the entire genetic information of the microbial communities in selected biogas plants up and down Germany. From the beginning of 2013, the Californian Joint Genome Institute will undertake the sequencing required. The biocomputational analysis will be performed at CeBiTec. Not an easy task, since the data will be supplied in billions of fragments stemming in turn from hundreds of organisms. Piecing together this huge jigsaw puzzle will be painstaking work.

Stained, they fluoresce under the microscope: a wide variety of microbes can be seen in a sample taken from a biogas plant. Researchers at Bielefeld University want to find out which ones do their job best. (Credit: Karsten Niehaus)

In Germany, there are more than 7,000 biogas plants which can supply over six million households with power. The plants are filled mostly with plant biomass like maize silage but also with agricultural waste materials like liquid manure and chicken manure. One of the key research questions is how the production of biogas can be optimised. For this reason, Bielefeld scientists Dr Alexander Sczyrba, Dr Andreas Schlüter, Dr Alexander Goesmann, Professor Dr Jens Stoye und Professor Dr Alfred Pühler want to know what microbes are responsible for the decomposition of biomass -- and which of them do it best. "We are interested in discovering the microbiology that is really behind the processes going on in a biogas plant; what micro-organisms play which role at which stage," explains Andreas Schlüter, whose research at CeBiTec is in the field of biogas production.

First genome deciphered

The researchers' work has already borne its first fruit. "At CeBiTec, we have managed to deci-pher the complete genome sequence of Methanoculleus bourgensis, a methane producer," reports Professor Pühler. By doing so, Bielefeld has sequenced the first genome for a methane-producing archaeon from a biogas plant -- a single-celled primordial bacterium which plays an important role in certain biogas plants. Now, the researchers want to go even further.

Putting the puzzle together

The project is part of the Community Sequencing Program, a public sequencing programme financed at the Joint Genome Institute by the US Department of Energy. While previous biogas studies have concentrated primarily on certain marker genes, now the entire genetic information of the microorganisms is to be studied. The American institute will produce more than one terabyte of sequence data for this, which is equivalent in volume to approximately 300 human genomes. This data will be supplied in a countless number of fragments, however, since even the most modern technology is not capable of reading all at once the millions of bases of which a microbial DNA molecule consists. Instead, the sequencing technologies supply vast quantities of overlapping sections of about 150 bases.

The DNA sequences will then be returned to Bielefeld in billions of fragments, which is where Alexander Sczyrba's Computa-tional Metagenomics team comes into play. They develop bioinformatic procedures for the reconstruction of genome sequences. Their task is to compare the data, recognise the overlaps and use them to reassemble the base sequence. "We are trying to complete a puzzle made up of billions of pieces, which also includes hundreds of different puzzles all mixed up," explains Sczyrba.

Single-cell genomics promises new insights

Quite incidentally, the Bielefeld researchers will be breaking new ground in genomics. An estimated 99 per cent of all microorganisms cannot be cultivated in the laboratory. A brand new technology, single-cell genomics, is to provide insights here by determining the genome sequence from single microbial cells. Knowledge of the identity and functions of hitherto completely unknown microorganisms is expected to be gained. During the joint project, the Joint Genome Institute will sequence approximately 100 single-cell genomes.

The researchers have scheduled roughly two years for their project, in which also Bielefeld doctoral students of the Graduate Cluster in Industrial Biotechnology (CLIB) are involved. At the end, they hope to have discovered the optimal microbial community for biogas plants -- and thus be in a position to make this process of generating energy even more efficient.

Background

Biogas plants produce methane through the fermentation of plant biomass, which can be used to generate power and heat. The decomposition of plant biomass and the production of biogas in agricultural biogas plants are brought about by microbes. This process, which is similar to what goes on in the digestive tract of cattle, has a neutral carbon dioxide balance and does not therefore contribute to global warming. Unlike other renewable energies, for example weather-dependent power sources like wind and solar, methane can be produced constantly and stored. This allows it to be converted into power or heat as required.

source:sciencedaily

New Method for Collagen Scaffolds: Slice, Stack, Roll

Dec. 27, 2012 — Tufts University School of Engineering researchers have developed a novel method for fabricating collagen structures that maintains the collagen's natural strength and fiber structure, making it useful for a number of biomedical applications.

Infographic illustration of bioskiving technique. (Credit: Qiaobing Xu)

Collagen, the most abundant protein in the body, is widely used to build scaffolds for tissue engineering because it is biocompatible and biodegradable. Collagen is, however, hard to work with in its natural form because it is largely insoluble in water, and common processing techniques reduce its strength and disrupt its fibrous structure.

The Tufts engineers' new technique, called bioskiving, creates collagen structures from thin sheets of decellularized tendon stacked with alternating fiber directions that maintain much of collagen's natural strength.

Bioskiving does not dilute collagen's natural properties, says Qiaobing Xu, assistant professor of biomedical engineering, and inventor of the new technique. "Our method leverages collagen's native attributes to take advantage of the well-organized micro/nanostructures that nature already provides," he says.

Xu and Kyle Alberti, a Ph.D. student in Xu's lab, describe their technology in a paper published online inAdvanced Healthcare Materials on December 12, 2012.

Slice, Stack, and Roll

In their research, Xu and Albert cut small sections of collagen from bovine tendons. Using a specialized detergent, the researchers decellularized the sections, leaving intact only the extracellular collagen matrix made of bundles of aligned collagen nanofibers.

Xu and Alberti sliced the sections into ultra-thin sheets using a microtome, and then stacked 10 slices, crisscrossing the sheets so that the fibers in one ran perpendicular to those above and below it. This process produced a scaffold material with tensile strength stronger than constructs made using common processing techniques, Xu notes.

The researchers also created tubular scaffolding by rolling layers of collagen sheets around Teflon-coated glass rods. The sheets were layered so that fibers ran along the length and the circumference of the rods. This process yielded tubes that were found to be stronger than similar tubes made of reconstituted collagen. They also maintained their highly aligned fiber structure.

"Alignment gives the scaffold the ability to guide the direction and orientation of cell growth," says Xu, who also has a faculty appointment at Tufts School of Medicine, "This capability is beneficial for tissue engineering applications where biocompatibility and the ability to guide unidirectional nerve growth are both desired, such as prosthetic or tissue engineering-based blood vessels or nerve conduits."

The work was supported by funding from a Tufts Faculty Research Award, the Charlton Award from Tufts School of Medicine, and a Tufts Neuroscience Institute Pilot Grant. It utilized facilities at the Harvard University Center for Nanoscale Systems(CNS), a member of the National Nanotechnology Infrastructure Network (NNIN), which is supported by the National Science Foundation under NSF award no. ECS-0335765.

source:sciencedaily.

Liquid Crystal Research May Lead to Creation of New Materials That Can Be Actively Controlled

Contributing geometric and topological analyses of micro-materials, University of Massachusetts Amherst mathematician Robert Kusner aided experimental physicists at the University of Colorado (UC) by successfully explaining the observed "beautiful and complex patterns revealed" in three-dimensional liquid crystal experiments. The work is expected to lead to creation of new materials that can be actively controlled.

Kusner is a geometer, an expert in the analysis of variational problems in low-dimensional geometry and topology, which concerns properties preserved under continuous deformation such as stretching and bending. His work over 3 decades has focused on the geometry and topology of curves, surfaces and other spaces that arise in nature, such as soap films, knots and the shapes of fluid droplets. Kusner agrees with physicist and lead author Ivan Smalyukh of UC Boulder that their collaboration is the first to show in experiments that some of the most fundamental topological theorems hold up in real materials. Their findings appear in the current early online issue of Nature.

UMass Amherst's Kusner explains, "There are two important aspects of this work. First, the experimental work by the Colorado team, who fabricated topologically complex micro-materials allowing controlled experiments of three-dimensional liquid crystals. Second, the theoretical work performed by us mathematicians and theoretical physicists while visiting the University of California Santa Barbara's Kavli Institute for Theoretical Physics (KITP). We provided the geometric and topological analysis of these experiments, to explain the observed patterns and predict what patterns should be seen when experimental conditions are changed."

Kusner was the lone mathematician among four organizers of last summer's workshop on "Knotted Fields" at KITP, which led to this work. The workshop engaged about a dozen other mathematicians and about twice as many theoretical and experimental physicists in a month-long investigation of the interplay between low-dimensional topology and what physicists call "soft matter."

In their experiments, the physicists at UC Boulder showed that tiny topological particles injected into a liquid crystal medium behave in a manner consistent with established theorems in geometry and topology, Kusner says. The researchers say they have thus identified approaches for building new materials using topology.

UC Boulder's Smalyukh and colleagues set up the experiment by first creating colloids, solutions in which tiny particles are dispersed but not dissolved in a host medium, such as milk, paint and shaving cream. Specifically, they injected tiny, different-shaped particles into a liquid crystal, which behaves something like a liquid and a solid. Once injected into a liquid crystal, the particles behaved as predicted by topology.

Smalyukh says, "Our study shows that interaction between particles and molecular alignment in liquid crystals follows the predictions of topological theorems, making it possible to use these theorems in designing new composite materials with unique properties that cannot be encountered in nature or synthesized by chemists. These findings lay the groundwork for new applications in experimental studies of low-dimensional topology, with important potential ramifications for many branches of science and technology."

For example, he adds, these topological liquid crystal colloids could be used to upgrade current liquid crystal displays like those used in laptops and television screens, to allow them to interact with light in new, more energy efficient ways.

source:sciencedaily.

Insect Assailants

Insect Assailants

Is this gold vending machine, the first to be installed in the U.S., going to become a commonplace invention or one bound for the footnotes of history?

Joe Raedle/Getty Images

Some inventions are so ubiquitous that it's difficult to imagine they started as an idea scribbled on paper and then a patent application submitted to, say, the U.S. Patent and Trademark Office (USPTO). Aluminum foil, adhesive bandages, the ballpoint pen, the computer mouse, the microwave oven -- these are just a few examples of great ideas that became indispensable products we now take for granted.

Nevertheless, of the 520,277 applications that inventors filed with USPTO in 2010, chances are that not even half will be granted patents, and far fewer will become commercial successes [source: USPTO]. For every new gadget that becomes a household name and changes our lives, there are thousands of others that languish in patent office files, unappreciated except perhaps as curiosities. Some of them are ingenious, but plagued with small but fatal flaws. Others are too outlandish to ever gain widespread acceptance. A few are simply ahead of their time.

In that spirit, here are 10 of the most outré technological advances from recent years -- inventions that push the boundaries of innovation, yet seem unlikely to gain widespread acceptance. Enjoy them with a caveat: There were people who scoffed at the notion that the motorized carriage would ever replace the convenience of having a horse, and others who figured that nobody would ever need or want to carry a telephone around in their pocket. Enjoy.

No mind control for these U.S. soldiers on patrol -- yet.

Marco di Lauro/Getty Images

The helmet used by the U.S. military has changed dramatically over the years. In World War I, the M1917/M1917A1 helmets, also known as "Doughboy" or "dishpan" helmets, protected the heads of American infantrymen. They were replaced in 1941 by the M-1 "steelpot," the standard-issue helmet in World War II, the Korean conflict and throughout the Vietnam War. By the 1980s, U.S. military helmets had evolved into a one-piece structure composed of multiple layers of Kevlar 29 ballistic fiber.

The helmet of the near future, however, may contain something more than extra protection from flying shrapnel. An Arizona State University researcher, working under a grant from the U.S. Defense Advanced Research Projects Agency (DARPA), is trying to develop a military helmet equipped with technology to regulate soldiers' brains. The technology is transcranial pulsed ultrasound, which delivers high-frequency sound waves to specific regions of the brain. Under the influence of these sound waves, neurons send impulses to their targets, exerting control over them. On the battlefield, this has enormous implications. Using a controller, a soldier could release ultrasound pulses to stimulate different areas of the brain. For example, he or she might want to be more alert after being awake for many hours or relax when it's time to catch some shuteye. The soldier might even be able to relieve stress or become oblivious to pain, eliminating the need for morphine and other narcotics.

Of course, some people think this type of neurotechnology is pure science fiction. Others worry that Uncle Sam is trying to take over the minds of its soldiers. After all, it's one thing to have a drill sergeant yelling in your ear. It's another thing completely to have one inside your head [source: Dillow].

A sketch of what the pencil-making device might look like

HowStuffWorks.com

U.S. businesses use about 21 million tons (19 million metric tons) of paper every year -- 175 pounds of paper for each American, according to the Clean Air Council. This has led to office recycling programs, "please think before you print" e-mail signatures and printers that offer double-sided printing. Now a trio of Chinese inventors hopes to add another device to the cubicle environment: the P&P Office Waste Paper Processor, which turns paper destined for recycling into pencils. The machine, looking a bit like a three-hole punch crossed with an electric pencil sharpener, was a finalist in the 2010 Lite-On Awards, an international competition that seeks to stimulate and nurture innovation.

Here's how the pencil-making gadget works: You insert wastepaper into a feed slot. The machine draws the paper in, rolls and compresses it, and then inserts a piece of lead from a storage chamber located in the top of the device. A small amount of glue is added before -- voilà -- a pencil slides out from a hole on the side. It's not clear how many pieces of paper form a single pencil, but you figure the average office worker could generate a decent supply of pencils in a month.

And that seems to be the biggest drawback to the pencil-producing gadget. How many No. 2 pencils can an office really use, given that most workers take notes on their tablet PCs or laptops? And how much glue and lead core do you need to buy to keep up with the overflowing paper recycle bin? Too much, we would suspect, which is why you may never see this gadget in your office supplies catalog [source: Bonderud].

The PrePeat, minus its plastic paper

Photo courtesy Sanwa Newtec Co., Ltd.

Printing has come a long way since the computer landed on the desktop. First, there were daisy-wheel printers, then dot-matrix printers, then inkjet and laser printers. The problem with all of these output devices, of course, is that they require paper -- lots of it -- and expensive consumables, like toner. Why can't someone invent an inkless, tonerless printer that allows the operator to reuse paper?

As it turns out, this isn't a new idea. Xerox has been working with so-called electronic paper since the 1970s. Its most promising solution is a type of paper called "Gyricon." A Gyricon sheet is a thin layer of transparent plastic containing millions of small oil-filled cavities. A two-colored bead is free to rotate inside each cavity. When a printer applies a voltage to the surface of the sheet, the beads rotate to present one colored side to the viewer, offering the ability to create text or pictures. The images will remain on the paper until it's fed through the printer once again.

A Japanese company, Sanwa Newtec, is offering its version of inkless, tonerless and rewritable printing technology. Its product is called the PrePeat rewritable printer, which, like the Xerox solution, requires plastic paper. But PrePeat uses a different technique to produce an image. Each sheet of paper comes embedded with leuco dyes, which change color with temperature -- colored when cool and clear when hot. The PrePeat printer, then, heats and cools the paper to first erase an image and then create a new image in its place. According to the company, a single sheet of paper can be reused 1,000 times before it needs to be replaced.

What's the catch? A single PrePeat printer costs almost $6,000, while a pack of 1,000 sheets of paper costs more than $3,300. If you're running a printing-intensive business, you might be able to recoup your investment over time. But the average PC user likely won't be willing to shell out that kind of money to replace a standard printer [source: Miller].

A NAV will be a lot smaller than the EMT Aladin airborne reconnaissance drone this German soldier is using for close area imaging during patrol on Oct. 17, 2010, in Afghanistan.

Miguel Villagran/Getty Images

Many people don't know it, but USPTO can apply a secrecy order to a patent if patent office staff and their military advisers think the idea could be used to threaten national security. Once the USPTO decides that a technology is no longer a threat, it can publish the patent and pave the way for commercialization. Some patents may remain cloaked under a secrecy order for one or two years; others languish for decades. More than 5,000 patents -- inventions we may never know or see -- currently have secrecy orders attached to them [source: Marks].

That's not the end of hush-hush inventions. Each year, the Pentagon sets aside billions of dollars to develop top-secret military weapons. This so-called "black budget" has grown tremendously since the Sept. 11 attacks, surpassing even the funds spent at the height of the Cold War. Some of that money has gone toward the development of nano air vehicles (NAVs), remote-controlled micro-drones that could easily infiltrate enemy territory. We all know how the U.S. military has used larger drones to conduct reconnaissance, transport supplies and even target individuals. Unfortunately, the larger attack drones, such as the MQ-1 Predator, can result in unwanted civilian casualties.

Lockheed Martin's Samarai micro-drone could solve that problem. Weighing a mere 5.29 ounces (150 grams) and boasting a 12-inch (30-centimeter) wingspan, the Samarai looks like a maple-seed whirligig, except this one comes with a miniature jet engine to provide thrust and a tiny flap on the trailing edge of the wing to control direction. In the near future, this nature-inspired micro-drone will snap photos using a camera mounted on the gadget's central hub. But the longer-term goals are to turn the Samarai or other similar micro-drones into armed attack vehicles capable of killing a single individual with little or no collateral damage [source: Weinberger].

Perpetual Printing

Perpetual Printing

Is this gold vending machine, the first to be installed in the U.S., going to become a commonplace invention or one bound for the footnotes of history?

Some inventions are so ubiquitous that it's difficult to imagine they started as an idea scribbled on paper and then a patent application submitted to, say, the U.S. Patent and Trademark Office (USPTO). Aluminum foil, adhesive bandages, the ballpoint pen, the computer mouse, the microwave oven -- these are just a few examples of great ideas that became indispensable products we now take for granted.

Nevertheless, of the 520,277 applications that inventors filed with USPTO in 2010, chances are that not even half will be granted patents, and far fewer will become commercial successes [source: USPTO]. For every new gadget that becomes a household name and changes our lives, there are thousands of others that languish in patent office files, unappreciated except perhaps as curiosities. Some of them are ingenious, but plagued with small but fatal flaws. Others are too outlandish to ever gain widespread acceptance. A few are simply ahead of their time.

In that spirit, here are 10 of the most outré technological advances from recent years -- inventions that push the boundaries of innovation, yet seem unlikely to gain widespread acceptance. Enjoy them with a caveat: There were people who scoffed at the notion that the motorized carriage would ever replace the convenience of having a horse, and others who figured that nobody would ever need or want to carry a telephone around in their pocket. Enjoy.

No mind control for these U.S. soldiers on patrol -- yet.

The helmet used by the U.S. military has changed dramatically over the years. In World War I, the M1917/M1917A1 helmets, also known as "Doughboy" or "dishpan" helmets, protected the heads of American infantrymen. They were replaced in 1941 by the M-1 "steelpot," the standard-issue helmet in World War II, the Korean conflict and throughout the Vietnam War. By the 1980s, U.S. military helmets had evolved into a one-piece structure composed of multiple layers of Kevlar 29 ballistic fiber.

The helmet of the near future, however, may contain something more than extra protection from flying shrapnel. An Arizona State University researcher, working under a grant from the U.S. Defense Advanced Research Projects Agency (DARPA), is trying to develop a military helmet equipped with technology to regulate soldiers' brains. The technology is transcranial pulsed ultrasound, which delivers high-frequency sound waves to specific regions of the brain. Under the influence of these sound waves, neurons send impulses to their targets, exerting control over them. On the battlefield, this has enormous implications. Using a controller, a soldier could release ultrasound pulses to stimulate different areas of the brain. For example, he or she might want to be more alert after being awake for many hours or relax when it's time to catch some shuteye. The soldier might even be able to relieve stress or become oblivious to pain, eliminating the need for morphine and other narcotics.

Of course, some people think this type of neurotechnology is pure science fiction. Others worry that Uncle Sam is trying to take over the minds of its soldiers. After all, it's one thing to have a drill sergeant yelling in your ear. It's another thing completely to have one inside your head [source: Dillow].

A sketch of what the pencil-making device might look like

HowStuffWorks.com

U.S. businesses use about 21 million tons (19 million metric tons) of paper every year -- 175 pounds of paper for each American, according to the Clean Air Council. This has led to office recycling programs, "please think before you print" e-mail signatures and printers that offer double-sided printing. Now a trio of Chinese inventors hopes to add another device to the cubicle environment: the P&P Office Waste Paper Processor, which turns paper destined for recycling into pencils. The machine, looking a bit like a three-hole punch crossed with an electric pencil sharpener, was a finalist in the 2010 Lite-On Awards, an international competition that seeks to stimulate and nurture innovation.

Here's how the pencil-making gadget works: You insert wastepaper into a feed slot. The machine draws the paper in, rolls and compresses it, and then inserts a piece of lead from a storage chamber located in the top of the device. A small amount of glue is added before -- voilà -- a pencil slides out from a hole on the side. It's not clear how many pieces of paper form a single pencil, but you figure the average office worker could generate a decent supply of pencils in a month.

And that seems to be the biggest drawback to the pencil-producing gadget. How many No. 2 pencils can an office really use, given that most workers take notes on their tablet PCs or laptops? And how much glue and lead core do you need to buy to keep up with the overflowing paper recycle bin? Too much, we would suspect, which is why you may never see this gadget in your office supplies catalog [source: Bonderud].

The PrePeat, minus its plastic paper

Photo courtesy Sanwa Newtec Co., Ltd.

Printing has come a long way since the computer landed on the desktop. First, there were daisy-wheel printers, then dot-matrix printers, then inkjet and laser printers. The problem with all of these output devices, of course, is that they require paper -- lots of it -- and expensive consumables, like toner. Why can't someone invent an inkless, tonerless printer that allows the operator to reuse paper?

As it turns out, this isn't a new idea. Xerox has been working with so-called electronic paper since the 1970s. Its most promising solution is a type of paper called "Gyricon." A Gyricon sheet is a thin layer of transparent plastic containing millions of small oil-filled cavities. A two-colored bead is free to rotate inside each cavity. When a printer applies a voltage to the surface of the sheet, the beads rotate to present one colored side to the viewer, offering the ability to create text or pictures. The images will remain on the paper until it's fed through the printer once again.

A Japanese company, Sanwa Newtec, is offering its version of inkless, tonerless and rewritable printing technology. Its product is called the PrePeat rewritable printer, which, like the Xerox solution, requires plastic paper. But PrePeat uses a different technique to produce an image. Each sheet of paper comes embedded with leuco dyes, which change color with temperature -- colored when cool and clear when hot. The PrePeat printer, then, heats and cools the paper to first erase an image and then create a new image in its place. According to the company, a single sheet of paper can be reused 1,000 times before it needs to be replaced.

What's the catch? A single PrePeat printer costs almost $6,000, while a pack of 1,000 sheets of paper costs more than $3,300. If you're running a printing-intensive business, you might be able to recoup your investment over time. But the average PC user likely won't be willing to shell out that kind of money to replace a standard printer [source: Miller].