ChemWeb Newsletter

Not a subscriber? Join now.October 4, 2005


In this issue The Alchemist covers water-repellent water, electronic pinball, and how smart concrete could save the levees. Also this week, a skin cancer pro-drug that exploits cancer cell chemistry to reduce side effects and a mercurial catch-22 for New Yorkers.

British scientists have developed a new class of pro-drug for treating skin cancer that might avoid the side effects of conventional treatments. Helen Osborn of Reading University says that the pro-drugs have lower overall toxicity because the cytotoxic drug itself is released only in the vicinity of malignant melanoma cells. The key to the new approach lies in exploiting the presence of high levels of the enzyme tyrosinase in melanoma cells. The enzyme is almost absent from other cells. The pro-drug is comprised the cytotoxic agent and a side-group that deactivates it. The enzyme removes the side-group exposing the cancer cell to the drug.

It is a classic catch-22: dredge mercury contaminated sediment from shipping channels and stabilize it prior to landfill but produce emissions on land despite stabilization or leave the sediment in situ and suffer marine emissions. That's the quandary facing environmental scientists after research by John Reinfelder of Rutgers University showed that even sediment mixed with cement prior to landfill releases mercury into the environment. Reinfelder studied the fate of mercury in sediments sent to landfill from shipping channels leading into the harbors in New Jersey and New York. "Our preliminary laboratory flux chamber results suggest that photochemistry is critical to mercury flux from both stabilized and unstabilized sediments," says Reinfelder.

Scientists at Pacific Northwest National Laboratory have discovered that a monolayer of water molecules sitting on a platinum substrate, behaves like a hydrophobic material and as such is a poor template for the growth of ice crystallites. Greg Kimmel and his colleagues demonstrated that at 60 Kelvin, water itself can become water repellent. The study could have important implications for researchers investigating the seeding of clouds, where ice is nucleated on particles in the atmosphere. The hydrophobic behavior of the water monolayer is explained by the way water molecules bond to the platinum and "ball up", precluding bonding to additional incident molecules.

A team of Ohio University and Brazilian physicists have discovered what happens when two molecules are held between electrodes. Molecular vibrations and strong electronic interactions, it seems, produce unexpected "transport channels" through which electrons can move. Electrons rattle through the molecules like a pinball, leaving all bells ringing (atoms moving). The team has found they can trap the electronic pinball momentarily in the molecule. This finding could take science another small step towards the realm of molecular electronics by allowing researchers to make transmission through molecular "wires" more efficient.

Smart concrete containing short carbon fibers can "detect" stress and tiny deformations in any structure from which it is built, according to its inventor Deborah Chung of the University of Buffalo. She says, the time is ripe for engineers to exploit this property in building flood defences and other structures that face potentially devastating stress from hurricanes and earthquakes. The presence of the carbon fibers means that the electrical resistance of the material can be monitoring by external metering to provide and early warning of imminent material failure.