Scott Miller, a chemist at Boston College in Massachusetts and graduate
student Greg Copeland, wanted to find catalysts for a reaction called
acylation—important in the drugs industry—which happens to produce
acid as a by-product. So they took a molecule, which they knew glows blue in the
presence of acid, and fixed it to a bead of resin. They figured that if they
could also attach a catalyst, the bead would glow during the reaction: the more
effective the catalyst, the brighter the glow.

The chemists tested their idea using four known catalysts on beads containing
the sensor molecule, all in a single container. Just as they expected, they
found the beads with the best catalyst glowed brightest and the worst stayed
dark (Journal of the American Chemical Society, vol 121, p 4306).

When used to hunt down new catalysts, the brightest beads can easily be
plucked out of the container for further study. James Morken, a chemist at the
University of North Carolina in Chapel Hill, calls Miller’s work a “great
˛ą»ĺ±ą˛ą˛Ôł¦±đ”.

About 8000 tonnes of musk fragrances are synthesised every year for perfumes,
cosmetics and soaps. For the past five years, researchers have been finding
synthetic musk compounds in fish and mussels and in human fat, milk and blood.
The compounds seem to build up through the food chain in much the same way as
polychlorinated biphenyls (PCBs) and some pesticides, such as DDT.

Now, for the first time, these molecules have been found in air samples.
Robert Gatermann and his colleagues at the Norwegian Institute for Air Research
in Tromsø found high musk concentrations in indoor air samples and much lower
concentrations—similar to PCB levels—in outdoor air. “I think it
comes from cosmetics and all kinds of cleaners or air freshener sprays,” he
says. Gatermann says that humans can build up the compounds in their bodies by
breathing in these organic pollutants, as well as by eating contaminated food.
The team’s results will appear in a future edition of the Journal of Chromatography.

Gerhard Rimkus at the Official Food and Veterinary Institute in
NeumĂĽnster, Germany, adds that exposure can also come from textiles that
are washed in powder containing musk compounds. Rimkus would like to see further
studies and risk assessments made of the potential threat from musk compounds.

Around the Chernobyl plant, an area about one and a half times the size of
Luxembourg has been declared off-limits for habitation or cultivation. In much
of the exclusion zone, radioactivity is still measurable. It now poses little
danger so long as it remains in the ground, but food grown in the area is unfit
to eat.

Caesium-137, which has a half-life of 30 years, is the most important
radio-nuclide left from Chernobyl’s catastrophic explosion in 1986.
Researchers have been looking for ways to prevent it getting into crops planted
in contaminated soil. Using lots of potassium fertiliser is one proven method,
as plants take up the potassium ion from soil in preference to caesium,
preventing further caesium uptake.

Now, Teresa Sauras Yera, a biologist at the University of Barcelona, has
found that mulching, the method used by farmers and gardeners to conserve
moisture and prevent weeds growing, does the job more cheaply and easily. With
colleagues in Spain and at the Institute of Agricultural Radiology in Kiev,
Sauras Yera added mulch to soil in the exclusion zone after planting oat seeds
over three successive years. One year, they covered the soil with black
polyethylene sheets. In the other two years, they used straw. Each year, they
saw a reduction of 30 to 40 per cent in the levels of radio-caesium in the oats
(Environmental Science & Technology, vol 33, p 882).

The researchers believe the mulch protects the plants’ leaves and roots from
radioactive particles carried by rain and wind. Since mulching is cheap, it
could be used to limit radioactive contamination, she says. However,
radioactivity levels near Chernobyl are still far too high to make the oats safe
for consumption.

But mulching still leaves the radioactive elements in the soil—so
attempts are being made to remove it. Slavik Dushenkov of the US biotech firm
Phytotech says the fast-growing cannabis plant, the source of hemp fibre, could
be an answer. Phytotech and the Ukrainian Academy of Agricultural Sciences in
Glukhov have been growing hemp around Chernobyl. After processing the plants,
they obtained clean hemp fibre and plant remains rich in caesium. The
contaminated remains were burnt in a sealed incinerator that caught all the
radioactive ash.

But so far, this method looks as if it could remove only about 1 per cent of
the caesium, as much of it is tightly bound to soil particles. “Maybe any one of
the three processes will not be economic, but all put together may provide
significant benefits,” Dushenkov says.

Confusion in people with Alzheimer’s disease is thought to be linked to loss
of memory, so when patients get lost, doctors assume they have forgotten where
they are going. But Charles Duffy of the University of Rochester, who has
studied how monkeys process visual patterns to tell them which way they are
moving, wondered if faulty vision processing also contributed to the
problem.

To test this, he and his colleagues asked 11 people with Alzheimer’s and 18
healthy subjects to watch patterns on a giant computer screen. The screen showed
dots streaming outwards from a spot, giving the impression that the observer is
moving forward. The team then tested the volunteers’ ability to detect these
patterns in the presence of other dots moving randomly.

If 15 per cent of the dots moved radially, the young and elderly healthy
people could pick out the origin of the radial pattern. But the Alzheimer’s
patients needed more than twice as many dots to be moving radially to identify
this (Neurology, vol 52, p 958). “In the noise-filled environment of
walking around, they are just not getting the same signal quality,” Duffy
concludes. “They can’t see where they are going.”

What’s more, six of the Alzheimer’s patients in the study had far more
trouble than the other five in interpreting the patterns. The same six people
also had more difficulty answering questions about the route they followed
through the hospital to get to the lab.

Duffy suspects that problems interpreting movement could be an early symptom
of Alzheimer’s disease. Physicians might be able to use his radial dot test to
diagnose the disease early and begin treatment, he suggests, perhaps preventing
the onset of more serious symptoms.

“Traditional energetic materials tend to be crystalline, like TNT,” says
Marcia Hohn of Britain’s Defence Evaluation and Research Agency (DERA). Such
propellants form powders that are difficult to handle because they are very
sensitive and ignite easily, so they are normally stabilised by adding a rubbery
polymer. As links form between the polymer’s long-chain molecules, the fuel
solidifies.

But solid fuel that is made this way does not melt. If something goes wrong
during processing, there is no way to recover the materials. And because the
fuel’s shape cannot be changed, it can be used only in the rockets it was
originally intended for.

“Now we have a rubber which can be recycled,” says Allan Fawcett, a chemist
at The Queen’s University of Belfast. Fawcett, whose work was funded by DERA,
started with a liquid polymer made up of molecules that include
oxygen-containing rings called furans. He then added a compound that binds to
the furan groups on different chains, linking the chains together.

When Fawcett heated the rubber to 150 °C, the reaction reversed and the
polymer molecules separated to form a liquid. Fawcett tried this procedure on a
sheet of rubber folded into a Z-shape. When he cooled it down again, he found
the three layers had joined without a seam.

While a few companies have developed other meltable rubber materials, Fawcett
says his furan-based system has the advantage that it will be easy to add
energy-rich groups such as nitrates to the chain of the polymer itself. If this
can be done, the rubber will both bind the fuel together and provide extra
energy. Hohn thinks that this is a strength of the system. “[Conventional]
rubber tends to be inert, so you’re diluting the energy of the whole
formulation,” she says. No one has previously made rubber that can contain
energetic molecules and has reversible cross-links, she says.

Alessandro Gandini of the French Engineering School of Paper and Printing in
Saint Martin d’Hères, who has done similar work on polymers, notes that
Fawcett’s form of rubber can be melted only once. The furan rings seem to form
permanent links between polymer chains after melting because of oxidation
reactions. Fawcett believes this will be easy to get around by adding a
stabilising chemical, but Gandini suggests the solution is to use a polymer with
fewer furan rings.

The new rubber may find numerous applications. Because it can be moulded and
shaped like plastic, it could be squeezed through plastics processors, so
anything that is currently made from plastic—pipes, pen caps,
cups—could now be made from Fawcett’s rubber. “I don’t know why you would
want to do that,” he admits. But, he says: “When bags were first made out of
plastic, people said, `Why don’t you just use paper?’ It takes time for anything
like this to get into use.”

Molecules such as DNA and proteins tend to interact by molecular recognition,
where two molecules—or segments within one molecule—are attracted to
each other because their shapes are complementary, or through surface properties
like hydrophobicity or hydrogen bonding. These forces are what make proteins
spontaneously fold into complex structures, or single strands of DNA zip up to
form a double helix. For years, chemists have used these principles to design
molecules. “But we really don’t know how to start pushing to larger sizes,” says
Ralph Nuzzo, a chemist at the University of Illinois at Urbana-Champaign.

At Harvard, George Whitesides and graduate students Insung Choi and Ned
Bowden may have the answer. The way proteins interact with smaller molecules,
known as “ligands”, inspired them to see if the same principles would work on a
much larger scale. They made hexagons 2.7 millimetres across and 1 millimetre
high out of a hydrophobic polymer called poly(dimethylsiloxane). To make parts
hydrophilic, they covered one face and several edges with tape and oxidised the
exposed surface.

To model a protein, the chemists glued several hexagons together to make
various shapes. For the ligands they used just one or two hexagons. Since
poly(dimethylsiloxane) is slightly denser than water, they could suspend their
hexagons in the interface between water and a denser, hydrophobic organic
solvent.

After swirling the suspended models about, the researchers discovered that
smaller “ligands” did indeed nestle into the pockets of larger “proteins” if the
hydrophobic edges matched. What’s more, the researchers could mimic a real
protein’s inherent preference for either left-handed or right-handed ligands
(see Diagram).
When they made two-hexagon ligands with hydrophobic edges either
on the upper left or on the upper right, they found that each ligand would join
only with a “protein” with the same “handedness”.

Whitesides says the attraction between the hexagons is driven by a reduction
in the overall energy of the interface between the liquids. The work will be
reported in the Journal of the American Chemical Society.

The technique may allow for very precise assembly of materials, the
researchers suggest. “This may be error-proof fabrication of electrical
devices,” Choi says, noting that it should be easy to put electrical devices on
each hexagon.

Before achieving that, however, the team will have to learn how to weld the
pieces together after they have self-assembled. At the moment, the aggregates
fall apart when removed from the interface between the liquids.

The test exploits “individual-specific autoantibodies”, antibodies which are
unique to each person. żěè¶ĚĘÓƵs at Miragen, a biotech firm in Irvine,
California, have coated paper with strips of proteins to which the antibodies
bind. When they place a blood sample on the paper then stain it, a series of
purple stripes appears, like a bar code, unique to the person who supplied the
sample.

Miragen’s test has already been used to track medical samples to avoid
mix-ups. But Vicki Thompson at Idaho National Engineering and Environmental
Laboratory in Idaho Falls thought the test might be useful in forensic labs. To
try it out, she collected blood samples from 10 volunteers and sent them to
Wyoming State Crime Laboratory in Cheyenne. At the lab, they were doctored to
create 422 samples like those found at crime scenes, for example where blood has
been dried on pavements or windscreens, or mixed with petrol.

Thompson and her colleagues analysed the samples using the antibody test and
correctly identified 384 of them. In addition, the test was far quicker and
cheaper than DNA tests. DNA testing can take weeks, but the new test takes only
two hours. “In a murder case with 10 suspects, DNA testing would cost you
$2000 to $12 000,” Thompson adds. “This test would only cost you
$200.”

Although the test is not yet accurate enough to stand up in court, it does
look promising, according to Tilton Davis at the Wyoming State Crime Laboratory.
“It would allow forensic samples that do not have DNA in them to be tested,” he
says. This could be important in solving rape cases in which the suspect has had
a vasectomy. His semen would contain antibodies, but no DNA.

Cyanobacteria, as blue-green algae are also known, grow in freshwater all
around the world. They produce a class of toxins called microcystins, which can
lead to tumours in humans and, in rare instances, can cause death by acute
poisoning.

“About 50 per cent of the time, big growths of algae are toxic,” says Linda
Lawton, a microbiologist at Robert Gordon University in Aberdeen. No
conventional water treatment is effective against microcystins, she says.

Lawton, Peter Robertson and their colleagues looked at titanium
dioxide—a pigment used in white paint and sun creams—which they
already knew promoted the oxidation of a variety of organic compounds in bright
light. They found that mixing a suspension of the white powder in water and
shining ultraviolet light onto it essentially degrades all the toxin
microcystin-LR in less than 20 minutes. The photocatalyst should work equally
well on other microcystins, Lawton says.

The researchers also investigated the toxicity of the treated water. In a
paper due to appear in Environmental Science & Technology they say
that as microcystin-LR disappeared, the water became increasingly less toxic to
brine shrimp.

Treating water with titanium dioxide and ultraviolet light should cost about
the same as existing treatments, Lawton says. And it could be even cheaper, if
the technique can be fine-tuned to work in sunlight. The technique should rid
water of other poisons, too, Lawton says. “It’s known that this mechanism can be
used to destroy a lot of different trace organic compounds, so it could also be
used on pesticides or other organic contaminants.”

Andrew Mills, a chemist and photocatalysis expert at the University of Wales,
Swansea, says Lawton’s work highlights the breadth of titanium dioxide
applications. “The more we use it, the more we wonder, what can’t it purify?” he
says.

Steven Offenbacher of the University of North Carolina at Chapel Hill says
that the mouth provides a “toxic reservoir” of several bacteria that can escape
into the bloodstream in people with gum disease, creating an inflammatory
response that triggers cardiovascular problems. There is some evidence that
people with severe gum disease are more likely to suffer from heart disease and
stroke.

Offenbacher and his colleagues have also been looking at premature birth,
which seems to be more common in women with severe gum disease. His preliminary
results suggest that gum disease bacteria are indeed to blame in some cases.

In one study, Offenbacher and his colleagues compared 10 premature babies
with 10 infants born at full term. Two of the premature babies, but none of the
normal ones, had antibodies to their mother’s oral bacteria. “This is evidence
of infection that affects the fetus,” Offenbacher says.

In industrialised countries, two-thirds of babies that die in infancy are
born prematurely. Offenbacher suspects that up to 18 per cent of premature
births might be triggered by gum disease in the mother.

Offenbacher is now planning a much larger study. If that confirms the link
between oral health and premature birth, he will investigate whether improved
oral hygiene will reduce the number of babies born early.