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World's Fastest Optical Chip
David Welch, cofounder of telecom startup Infinera, CA holds up a rigid 2cm-wide strip featuring
four patterned, gold-colored rectangles. It's made of indium phosphide, a semiconductor prized for
its optical properties. The chip's simple appearance belies its complex engineering and gives little
hint that it could be the key to cheaply supplying the bandwidth the world is increasingly
demanding.The gadget is called a photonic integrated circuit, and it represents an important
practical advance in optical data transmission.
Since the early 1990s, such transmission has increasingly relied on a technique called wavelength
division multiplexing (WDM). With WDM, data is encoded on as many as 80 laser beams, each
having a different wavelength. Those beams are then combined for a trip down an optical fiber
thinner than a human hair. At a node on the other end of the fiber, the beams are split into their
constituent wavelengths, and the information is turned into the electrical signals that reach our
computers. The optical equipment required to do all this includes lasers that send light, multiplexers
that split it up or recombine it, modulators that encode it with data, and detectors that receive it.
Traditionally, these devices have been housed in their own little packages, each about the size of a
pack of gum, and combinations of them were bulky, expensive, and sometimes unreliable. Infinera-founded in 2001 by veteran executives and technologists from optical--telecom leaders like Ciena
and JDS Uniphase--set out to put dozens of such components on a chip, the way electrical engineers
combine transistors in an electronic integrated circuit. "What nobody had tried to do was essentially
put an entire WDM system on a pair of chips [one to send, the other to receive], and nobody had
tried to commercially manufacture it," says Welch. Infinera not only tried to do both but succeeded.
In 2004 the company introduced the first large-scale photonic integrated circuit--a chip with 50
nanoscale optical components patterned into its surface. Previously, other optical-chip
manufacturers had managed to integrate only a few such devices on a single chip. The first Infinera
device was capable of sending or receiving 100 gigabits of information per second. Now the
company has demonstrated a 400-gigabit chip and is well along in the development of what it
describes as the fastest optical chip in the world--a 1.6-terabit version that it expects to
commercialize within several years. The four gold patches on the chip in Welch's hand contain an
astonishing total of 240 patterned optical components.
Of course, despite the theoretical advantages of an "all-optical Internet," no network is based
entirely on optics. Equipment at network nodes converts optical signals to electrical ones so it can
clean them up and amplify them, or deliver them to a computer. Infinera's technology does this, too,
passing some jobs off to microprocessors on a circuit board that will then transfer them back.
But the photonic integrated circuit reduced the cost and complexity of the conversion process. This
advantage, in turn, allowed Infinera to promote a new network architecture--essentially, one with
more network nodes. Other companies had tried to keep costs down by reducing the number of
nodes, with their traditionally bulky optical devices.Having more nodes means more flexibility to
add access points and easier maintenance and fault detection. It thus makes it easier to combine the
benefits of optics and electronics. And the Infinera package--chips and circuit boards--take up onefifth the space of conventional technology.
Late last year the Internet2 consortium--a group of more than 300 U.S. government, university, and
corporate research centers that need high bandwidth to share everything from particle-physics data
to medical images--began deploying a new optical network that uses Infinera's systems. "Infinera's
technology is unique," says Steve Cotter, director of network services at Internet2.
Demand for Internet video and voice services is exploding, threatening to overwhelm the typical
broadband connection, which transmits between one and six megabits per second. "Photonic
integration becomes the technology that enables the Internet to grow."
Silicon 'Lego bricks' used to build 3D chips
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1.Pyramid-shaped teeth around the edges of one piece of silicon fit neatly into a matching set of holes on another
2. Matching sets of teeth and holes can precisely align separate silicon chips, with 200nm accuracy
The vast majority of modern electronics are etched onto flat silicon wafers and increasing their
speed normally involves squeezing more components onto the same surface area. Now researchers
are trying a different approach, by building electronics in three dimensions, typically by layering
individual silicon wafers on top of one another. Prototype 3D devices such as MIT's seven-layer
turbine-on-a-chip are currently assembled using a machine that lines them up visually, using
cameras to line-up markers on the surface of different wafers. Accuracy is crucial as the electronic
components on each chip must be carefully aligned up in order to function together properly.
Michael Kraft and colleagues at the University of Southampton, UK, have developed wafers fitted
with matching sets of pegs and holes, resembling those found on Lego bricks. Tests suggest that
this could provide a better construction method as microscopic features are more accurately lined up.
"Our technique is simpler and uses standard silicon processing equipment," says Kraft. He and
colleagues tested their stackable electronics using two silicon chips, each 2cm to a side.
Ten tiny pyramids are positioned along each edge of one of the wafers on the underside of angled
cantilevers (see graphic, right). These pyramids measure 500 µm wide at their base and 100 µm
wide at their tip. The matching wafer has a pattern of ten square holes along each of its edges. Both
features are created using acid and ion etching techniques that are standard in commercial silicon
processing. The researchers then simply lined up the edges of the two chips by hand and pressed
them together. The pyramids fit neatly into the holes and the two wafers can then be permanently
bonded together using 400ºC heat in a nitrogen atmosphere.
Images taken with a scanning electron microscope show that the two chips align to within 200 nm
accuracy – roughly five times better than with the camera-based technique. Kraft says the next step
is to use larger silicon wafers before developing functional electronics using
Nanoscopic 'coaxial cable' transmits light
A way to make nanoscopic metal cables transmit light could lead to innovations in solar cells,
artificial retinas and quantum computing components, say researchers. The trick is to shrink a
coaxial cable by a factor of 10,000 so the diameter is smaller than the wavelength of visible light.
Ordinary coaxial cable, or coax, consists of a central wire, surrounded by a layer of a nonconductive
"dielectric" material – typically a plastic – all wrapped in a metal sheath. The structure guides radio
waves along the surface of the central wire, so the waves pass through the dielectric material.
Cables a few millimetres in diameter carry video signals between DVD players, video recorders,
cable boxes, satellite antennas, and television sets. The wavelengths involved are several times the
cable diameter.
"Our coax works just like the one in your house, except now for visible light," says Jakub
Rybczynski from Boston College, US, who led the research. The big difference is the cable is
nanoscopic, measuring only 300 nm in diameter. It is shorter than the shortest visible wavelength
and also invisible to the human eye.
A carbon nanotube replaces the inner wire, a film of aluminium oxide replaces the plastic layer and
a coating of chromium or aluminium replaces the outer sheath.Normally light waves cannot
penetrate structures smaller than their length. But a length of nanotube protrudes from the end of the
cable and acts as an optical antenna to guide the light into the structure. Light waves can then travel
through the aluminium oxide layer, guided in the same way that a normal coaxial cable guides radio
waves.
The nanocables are not candidates to replace optical fibres. So far the longest ones stretch only 20
µm, and longer cables will only carry light a maximum of about 50 µm– roughly 100 wavelengths.
However, being able to transmit light on the nanoscale scale could have a range of potential
applications As the nano-guides are smaller than a wavelength, their behaviour is governed by
quantum mechanics. "It's possible we could use this for quantum computers”. However, the team
first target is to increase the efficiency of energy conversion in solar cells by tightly packing
together arrays of nano-coax filled with photovoltaic material rather than aluminium oxide.
Another possibility is to assemble arrays with optical antennas on one end and electrical output at
the other to serve as artificial retinas for people with impaired vision, he says.
Journal reference: Applied Physics Letters
New Generation of Optical Molecules
The internet could soon shift into overdrive thanks to a new generation of optical molecules
developed and tested by a team of researchers from Washington State University, the University of
Leuven in Belgium and the Chinese Academy of Science in China. The new materials, organic
molecules known as chromophores, interact more strongly with light than any molecules ever tested.
That makes them, or other molecules designed along the same principles, prime candidates for use
in optical technologies such as optical switches, internet connections, optical memory systems and
holograms. The molecules were synthesized by chemists in China, evaluated according to
theoretical calculations by a physicist at WSU and tested for their actual optical properties by
chemists in Belgium.
The team’s findings are published in the January issue of the journal Optics Letters.
Ever since optical technologies became prominent in the 1970s, researchers have tried to improve
the materials used to handle light. In 1999, Kuzyk at WSU, discovered a fundamental limit to how
strongly light can interact with matter. He went on to show that all molecules examined at that time
fell far short of the limit. Even the best molecules had 30 times less “optical brawn,” as he calls it,
than was theoretically possible. The molecules described in the new report break through this longstanding ceiling and are intrinsically 50 % better than any previously tested, which means they are
far more efficient at converting light energy to a useable form.
Earlier this year Kuzyk and two WSU colleagues published theoretical guidelines describing
molecular structures that should excel at interacting with light. "We found an excellent agreement
with Kuzyk's theoretical results,” said lead author of the current work Perez-Moreno. “We use the
quantum limits to try to get a clearer view of the nonlinear optical interaction and we wish to unveil
the unifying principles behind the interaction of light and matter—a very ambitious goal. This
summer we set some of the foundations of the quantum limits framework. "The new design
parameters call for a molecular structure that increases a property known as the “intrinsic
hyperpolarizability,” which reflects how readily electrons in the molecule deform when the
molecule mediates the merger of two photons into one, an action which is the basis of an optical
switch.Other researchers in the field hailed the breakthrough.
In the new designs, each molecule has a component at one end that donates an electron and a
component at the other end that accepts an electron. In between is the “bridge” portion of the
molecule. Previous efforts to boost the interaction with light focused on “smoothing out” the bridge
to allow electrons to flow more easily from donor to acceptor end. Kuzyk’s calculations showed
that a more “bumpy” structure actually enhanced the interaction with light. Quantum mechanics
explains the behavior of electrons in this situation, Kuzyk said.“When the electron is all spread out,
it can be interfering with itself. By inserting these speed bumps, you’re causing it to bunch up in
certain places, and preventing it from interfering with itself.”The molecules described in the current
report have just one “speed bump;’ now that researchers have confirmed that the theoretical designs
work, they are synthesizing molecules with more bumps.
He said that for use in optical switches or other products, the molecules would probably be
embedded in a clear polymer that would provide structural assets such as the ability to be formed
into a thin film or into fibers, molded into other shapes or used to coat circuits or chips.
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New Wires Could Create Better Nanotube Devices
A team of researchers at Rensselaer Polytechnic Institute has created hybrid structures that combine
the best properties of carbon nanotubes and metal nanowires. The new structures, which are
described in a recent issue of Applied Physics Letters, could help overcome some of the key hurdles
to using carbon nanotubes in computer chips, displays, sensors, and many other electronic devices.
The impressive conductivity of carbon nanotubes makes them promising materials for a wide
variety of electronic applications, but techniques to attach individual nanotubes to metal contacts
have proven challenging. The new approach allows the precise attachment of carbon nanotubes to
individual metal pins, offering a practical solution to the problem of using carbon nanotubes as
interconnects and devices in computer chips.
"This technique allows us to bridge different pieces of the nanoelectronics puzzle, taking us a step
closer to the realization of nanotube-based electronics," said Fung Suong Ou, the paper's main
author As chip designers seek to continually increase computing power, they are looking to shrink
the dimensions of chip components to the nanometer scale, or about 1-100 billionths of a meter.
Carbon nanotubes and nanowires that became available in the 1990s are promising candidates to act
as connections at this scale, according to Ou, because they both possess interesting properties.
For example, carbon nanotubes display amazing mechanical strength, and they are excellent
conductors of electricity, with the capacity to produce interconnects that are many times faster than
current interconnects based on copper. Gold nanowires also have very interesting optical and
electrical properties, and they are compatible with biological applications, Ou said.
"In order to take full advantage of these materials, we demonstrate the idea of combining them to
make the next generation of hybrid nanomaterials," he said. "This approach is a good method to
marry the strengths of the two materials."The metal nanowires in this technique are made using an
alumina template that can be designed to have pore sizes in the nanometer range. Copper or gold
wires are deposited inside the pores, and then the entire assembly is placed in a furnace, where a
carbon-rich compound is present. When the furnace is heated to high temperatures, the carbon
atoms arrange themselves along the channel wall of the template and the carbon nanotubes grow
directly on top of the copper wires. It's a really easy technique, and it could be applied to a lot of
other materials," Ou said. "The most exciting aspect is that it allows you to manipulate and control
the junctions between nanotubes and nanowires over several hundred microns of length. The
alumina templates are already mass-produced for use in the filter industry, and the technique can be
easily scaled up for industrial use."
To date the team has made hybrid nanowires that combine carbon nanotubes with both copper and
gold. But they also are currently working to connect carbon nanotubes to a semiconductor material,
which could be used as a diode, according to Ou.
New Material with a Negative Refractive Index for Visible Light
For the first time ever, researchers at the U.S. Department of Energy's Ames Laboratory have
developed a material with a negative refractive index for visible light. Costas Soukoulis, working
with colleagues in Karlsruhe, Germany, designed a silver-based, mesh-like material that marks the
latest advance in the rapidly evolving field of metamaterials, materials that could lead to a wide
range of new applications as varied as ultrahigh-resolution imaging systems and cloaking devices.
The discovery, detailed in the current issues of Science of Optic Letters, and noted in the journal
Nature, marks a significant step forward from existing metamaterials that operate in the microwave
or far infrared - but still invisible- regions of the spectrum. Those materials, announced this past
summer, were heralded as the first step in creating an invisibility cloak.
Metamaterials, also known as left-handed materials, are exotic, artificially created materials that
provide optical properties not found in natural materials. Natural materials refract light, or
electromagnetic radiation, to the right of the incident beam at different angles and speeds. However,
metamaterials make it possible to refract light to the left, or at a negative angle. This backwardbending characteristic provides scientists the ability to control light similar to the way they use
semiconductors to control electricity, which opens a wide range of potential applications.
"Left-handed materials may one day lead to the development of a type of flat superlens that
operates in the visible spectrum," said Soukoulis, "Such a lens would offer superior resolution over
conventional technology, capturing details much smaller than one wavelength of light to vastly
improve imaging for materials or biomedical applications," such as giving researchers the power to
see inside a human cell or diagnose disease in a baby still in the womb.
The challenge that Soukoulis and other scientists who work with metamaterials face is to fabricate
them so that they refract light at ever smaller wavelengths. The "fishnet" design developed by
Soukoulis' group and produced by researchers at the University of Karlsruhe was made by etching
an array of holes into layers of silver and magnesium fluoride on a glass substrate. The holes are
roughly 100 nm wide. For We have fabricated for the first time a negative-index metamaterial with
a refractive index of -0.6 at the red end of the visible spectrum (wavelength 780 nm)," said
Soukoulis. "This is the smallest wavelength obtained so far."
While the silver used in the fishnet material offers less resistance when subjected to electromagnetic
radiation than the gold used in earlier materials, energy loss is still a major limiting factor. The
difficulties in manufacturing materials at such a small scale also limit the attempts to harness light
at ever smaller wavelengths. "Right now, the materials we can build at THz and optical wavelengths
operate in only one direction," Soukoulis said, "but we've still come a long ways in the six years
since negative-index materials were first demonstrated. However, for applications to come within
reach, several goals need to be achieved. First, reduction of losses by using crystalline metals and/or
by introducing optically amplifying materials; developing three-dimensional isotropic designs
rather than planar structures; and finding ways of mass producing large-area structures."
Self-Cleaning surfaces with “Lotus” laser treatment
Dutch scientist has used a femtosecond laser to give plastic a self-cleaning surface like that of a
lotus leaf, which is so effective cups made of it may not need to be washed after use.
Max Groenendijk of the Applied Laser Technology Group of the University of Twente used the
ultra fast femtosecond laser to create the surface which has many potential domestic and industrial
applications.
The lotus leaf is covered in tiny pillars with a waxy layer on top. Water drops are lifted by these
pillars, form a spherical shape and roll off taking dirt particles with them. Groenendijk set out to
create similar surfaces using the laser to eliminate the need for wax. The light pulses of the
femtosecond laser are so short that they can be seen as light ‘bullets’ with which the surface is
bombed.The laser is applied in two separate steps. During the first step, the surface gets a fine ripple
structure. This is caused by a self-organising effect that works for almost all kinds of surfaces whenever the laser removes some material, a pattern of ripples is formed at the bottom. It is
possible to influence this pattern with parameters like speed, intensity and polarisation.
The second step is to write a pattern of perpendicular lines which leaves an array of pillars. These
pillars then already have the fine pattern caused by the first step. This double structure replaces the
need to have wax on the pillars, and makes the surface highly hydrophobic.
Treating repeated surfaces this way would be too expensive, but by using a mould, a series of
surfaces can be produced in a simple, economic way. According to Groenendijk, the structure can
dramatically improve the surface properties even for materials that are already quite hydrophobic.
Unlike in an unstructured, smooth surface, where droplets can still smear a little, the structured
surface gives the same spherical drops as the lotus plant.
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Scientists Stabilize Platinum Electrocatalysts For Use In Fuel Cells
Platinum is the most efficient electrocatalyst for accelerating chemical reactions in fuel cells for
electric vehicles. In reactions during the stop-and-go driving of an electric car, however, the
platinum dissolves, which reduces its efficiency as a catalyst. This is a major impediment for
vehicle-application of fuel cells.
Now, scientists at the U.S. Department of Energy's Brookhaven National Laboratory have
overcome this problem. Under lab conditions that imitate the environment of a fuel cell, the
researchers added gold clusters to the platinum electrocatalyst, which kept it intact during an
accelerated stability test. This test is conducted under conditions similar to those encountered in
stop-and-go driving in an electric car. The research is reported in the current issue of Science.
"Fuel cells are expected to become a major source of clean energy, with particularly important
applications in transportation," said coauthor Radoslav Adzic. "Despite many advances, however,
existing fuel-cell technology still has drawbacks, including loss of platinum cathode electrocatalysts,
which can be as much as 45 % over five days, as shown in our accelerated stability test under
potential cycling conditions. Using a new technique that we developed to deposit gold atoms on
platinum, our team was able to show promise in helping to resolve this problem. The next step is to
duplicate results in real fuel cells."
A hydrogen-oxygen fuel cell converts hydrogen and oxygen into water and, as part of the process,
produces electricity. Platinum electrocatalysts speed up oxidation and reduction reactions.
Hydrogen is oxidized when electrons are released and hydrogen ions are formed; the released
electrons supply current for an electric motor. Oxygen is reduced by gaining electrons, and in
reaction with hydrogen ions, water, the only byproduct of a fuel cell reaction, is produced.
In the unique method developed at Brookhaven, the researchers displaced a single layer of copper
with gold on carbon-supported platinum nanoparticles. After being subjected to several sweeps of
1.2 V, the gold monolayer transformed into three-dimensional clusters. Using x-rays as probes, a
scanning transmission microscope, and electrochemical techniques in the laboratory, the scientists
were able to verify the reduced oxidation of platinum and to determine the structure of the resulting
platinum electrocatalyst with gold clusters, which helped them to gain an understanding of the
effects of the gold clusters. In the Brookhaven experiment, the platinum electrocatalyst remained
stable with potential cycling between 0.6 and 1.1 V in over 30,000 oxidation-reduction cycles,
imitating the conditions of stop-and-go driving. "The gold clusters protected the platinum from
being oxidized," Adzic said. "Our team's research raises promising possibilities for synthesizing
improved platinum-based catalysts and for stabilizing platinum and platinum-group metals under
cycling oxidation/reduction conditions
Nanosized nuclear batteries
Engineering physics researchers at the University of Wisconsin-Madison are devising a unique
"blanket" that will enable them to squeeze as much electricity as possible from nuclear-powered
batteries the size of a grain of coarse salt. Such batteries, which exploit the natural decay of
radioisotopes to generate electricity, could provide virtually indefinite power for micro-technologies
like small robots for military applications or sensors that monitor a building's health.
Other technologies such as fuel cells, chemical batteries or turbine generators also might work in
micro-scale applications, said lead author James Blanchard. ‘But all of them are short-lived,’ he
said. ‘They either need to be recharged or refuelled. Our niche is things that need to be placed and
ignored, and just keep running for years.’Nuclear microbatteries convert heat or energy to
electricity more efficiently when they are hot, so it makes sense to insulate them, said Blanchard.
‘The better the insulation, the hotter the source gets, so the more efficient the battery can be,’ he
said.However, insulating a millimeter-square battery in a way that minimizes heat loss is no easy
task. Multifoil insulation is an effective macro-level insulator that combines several thin layers of
foil each separated by a vacuum. ‘They work because they're radiating heat from one layer to
another, as opposed to conducting heat through a solid,’ said Blanchard.For the microscale,
however, multifoil insulation is far too thick. So, capitalising on the layered concept, which reduces
heat radiation for a fixed temperature drop, Blanchard et al. decided to sandwich semicircular
silicon oxide pillars, which are poor conductors, between very thin silicon sheets.
’You want as little conduction through these pillars as possible,’ said Blanchard. He now is
experimentally verifying what his computer models suggest-that heat is radiating through the silicon
layers without much heat loss. ‘The prototypes he built are a little thicker than the ones we
ultimately want to get, but they're consistent with his models,’ said Blanchard.
Implementation for this promising technology, they say, is a couple of years down the road. ‘It
looks like we'll have an effective insulator that's better than any solid-and better, even, than some of
the multi-foil insulations that you can buy commercially,’ said Blanchard.
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Scientists Discover How Body Fights To Control Spread Of Cancer
Scientists at the University of Liverpool have found how two molecules fight in the blood to control
the spread of cancer cells. The researchers discovered that a large protein, which forms a protective
shield around cancer cells and prevents them from causing secondary tumours, is attacked by a
small protein that exists in the blood.
In diseases such as breast, lung and colorectal cancer, infected cells lose growth control and
eventually form tumours at these sites. If caught early these tumours can be effectively removed
surgically. However, when the cancer cells have invaded the blood, the effectiveness of surgery is
reduced. Cancerous cells that have entered the blood, however, are still prevented from causing
further disease by the protective shield of a protein called MUC1 in which the cancerous cells are
eventually destroyed by our immune system. Scientists have now discovered how this protective
shield is broken down, allowing cancer to spread throughout the body.
Dr Lu-Gang Yu, lead author, explains: "MUC1 on the cell surface prevents the cancer cells from
attaching to the blood vessel wall which causes secondary tumours. We have discovered that a
small protein called galectin-3, attacks MUC1 and breaks up its protective shield, forcing large
areas of the cancer cell to become exposed. The exposed areas of the cell allow the cancer to attach
to the blood vessel wall. The cancer cells then eventually penetrate the blood wall to form tumours
at secondary sites."The attachment of cancer cells to the blood vessel wall is one of the key steps in
the spread of cancer. It has been known for a few years that galectin-3 concentration is significantly
higher in the blood of cancer patients than in healthy people but until now scientists did not know
whether this increase played any role in the spread of cancer. Our study indicates that galectin-3
may play a critical role and may have significant implications for future developments of drugs for
the treatment of the disease."
Journal reference: Journal of Biological Chemistry.
Scientists Find Guardian Gene's Choices Crucial To Stopping Cancer Process
Scientists at the Jefferson University in Philadelphia have uncovered a novel pathway by which the
anti-cancer gene p53 springs into action, protecting a damaged cell from becoming cancer. The
gene can either halt the cell's growth or send it spiraling toward certain death. How this choice is
made, the researchers say, could have implications for future strategies in chemotherapy drug
development.
According to Steven McMahon, who led the work, the p53 gene's -- or rather its protein's -- ability
to direct a damaged cell to either stop growing or commit suicide depends on turning on separate
groups of target genes. He and his co-workers have found that after a cell's DNA is damaged, the
p53 protein's ability to bind to the DNA can be affected. Two enzymes, hMOF and TIP60, can
chemically alter an amino acid, lysine 120, at the binding site, in turn influencing p53's decision on
which target genes to turn on. The alteration can short-circuit p53's ability to cause the damaged cell
to commit suicide, though it can still stop cell growth, suggesting that this change may help explain
a mechanism behind p53's choice. They report their findings in the journal Molecular Cell.
"It's been known that p53 can induce cell cycle arrest or apoptosis (programmed cell death) as a
way of eliminating developing cancer cells in response to cell damage, but no one has known how
the choice is made," says Dr. McMahon. "This work narrows how the decision is made.The
findings could have implications for future drug development strategies. Most chemotherapy
strategies are aimed at getting cancer cells to die. Figuring out what pathways p53 uses to cause that
versus cell cycle arrest is important. It looks like this new modification that we have identified helps
p53 make that decision."
"p53 is such an important player in the cancerous process -- it's nearly always mutated or
inactivated in cancer -- that continuing to understand more about how it works will likely have
significant implications for cancer research," says Dr. McMahon. "We would like to understand the
interplay between this newly identified pathway and others involved in p53 and cancer. Since p53
can make this decision, this might give some insight into which function of p53 is more important
in which tissues. For example, K120 (lysine 120) mutations cause tumors in the prostate, but are not
so much involved in causing immune system cancers such as lymphomas. That could suggest that
p53's potential to cause cell death could be more important in certain tissues than in others. In the
future, if someone could develop therapies that could specifically activate p53's potential to drive
programmed cell death versus the cell cycle arrest potential, it might influence how a doctor might
choose to treat a certain type of cancer.
"This may potentially enable the development of a cancer drug that would stimulate the enzymes to
promote this modification driving p53 to apoptosis."
Anti-cancer chicken eggs produced
GM chickens could be a route to faster, cheaper drugs
UK scientists have developed genetically modified chickens capable of laying eggs containing
proteins needed to make cancer-fighting drugs. The breakthrough has been announced by the same
research centre that created the cloned sheep, Dolly: The Roslin Institute. Professor Harry Griffin,
director of the institute says it has produced five generations of birds that can produce useful levels
of life-saving proteins in egg whites. The work could lead to a range of drugs that are cheaper and
easier to make. "The idea of producing the proteins involved in treatments in flocks of laying hens
means they can produce in bulk, they can produce cheaply and indeed the raw material for this
production system is quite literally chicken feed."
Roslin has bred some 500 modified birds. Their existence is the result of more than 15 years' work
by the lead scientist on the project, Dr Helen Sang. But it could be another five years before patient
trials get the go-ahead and 10 years until a medicine is fully developed, the Roslin Institute
cautioned.
Therapeutic proteins such as insulin have long been produced in bacteria; but there are some
complex proteins that can only be made in the more sophisticated cells of larger organisms.
Scientists have successfully made a range of these molecules in the milk of genetically modified
sheep, goats, cows and rabbits. The work at Roslin shows it is now possible to use chickens as
"biofactories", too.
Some of the birds have been engineered to lay eggs that contain miR24, a type of antibody with
potential for treating malignant melanoma, a form of skin cancer. Others produce human interferon
b-1a, which can be used to stop viruses replicating in cells. The proteins are secreted into the whites
of the eggs. It is a fairly straightforward process then to extract and purify them.
Dr Sang said the team was highly encouraged by the level of the birds' productivity, but further
improvements were required. "We're probably getting a high enough productivity if you want to
make a very active protein like interferon, but not enough yet if you want to make an antibody
because people need large doses of these over long periods; so one of our next challenges is to try to
increase the yield in egg white.Chickens had some advantages over other animals for "pharming"
because their lifecycles were shorter. Once you've made the transgenic birds, then it's very easy;
once you've got the gene in, then you can breed up hundreds of birds from one cockerel - because
they can be bred with hundreds of hens and you can collect an egg a day and have hundreds of
chicks in no time," she explained.
Details of the latest work are published on Proceedings of the National Academy of Sciences
(PNAS).
The Roslin team also expects its engineered chickens to provide new insights into aspects of
reproductive biology. It says the ability to modify birds' embryos will allow researchers to study
fundamental processes that control the very early development of vertebrates.
'Scintillating' Materials against Cancer
Using materials that flash when struck by certain types of radiation, sensors developed in a new
laboratory at The University of Alabama might help doctors treat cancer, customs agents scan for
dirty bombs, and scientists study the furthest reaches of the universe.
Scientists and students working in the lab are looking at several possible uses for scintillating
materials that have been developed recently, said lead author. Richard Miller. These include a
sensor that would help doctors more accurately aim proton beams used in cancer radiation therapy.
"As much as possible, you want to focus the radiation on the bad cells and keep it away from the
good ones," Miller said. "We think sensors using these new materials might help us do a better job
of that.Scintillating materials flash or glow when they are hit by certain types of high energy
radiation, which can include X-rays and gamma rays, or by particles such as cosmic rays. The
intensity of the flash changes with the energy of the radiation, so you can infer the energy of the
incident radiation, and in some configurations the direction and type of radiation. “
In addition to several possible applications in nuclear medicine, scintillating sensors could be used
by homeland security to screen large port or airport facilities for telltale signs of illegal radioactive
materials. Advanced scintillators also have significant applications in astrophysics and planetary
exploration.Because they react to otherwise "invisible" radiation but flash in visible light, these
scintillating materials might also be coupled with other sensors to create powerful telescopes that
astronomers could use to study the most energetic stars and the most powerful explosions in the
universe.Miller's group is also looking at sensors that might help scientists "prospect" on other
planets without leaving orbit by picking up the unique signatures of radiation coming up from
different elements on a planet's surface.