New Worlds: Better bonding

Real-time water pollution monitoring; Israeli scientists mourn De Gennes.

By JUDY SIEGEL-ITZKOVICH
copper atom 88 (photo credit: )
copper atom 88
(photo credit: )
Scientists at the Technion-Israel Institute of Technology and colleagues in New York have found an original way to improve bonding between materials. The importance of this discovery to microelectronics devices translates into improved performance and reliability. In addition, this discovery could be used in nanometric devices that contain organic molecules and need to withstand high temperatures. Prof. Moshe Eizenberg of the materials engineering department and the Russell Berrie Nanotechnology Institute, together with Prof. Ganapathiraman Ramanath of the Rensselaer Polytechnic Institute in Troy, New York, published in Nature their work on bonding and adhering materials using nanolayers. These are short organic chains, each containing groups of atoms that bond to the appropriate surface. The concrete example upon which the Nature article is based is an original interface between copper layers and silicon oxide (silica) using a nanolayer inserted as a diffusion barrier - namely, in order to prevent failure of the devices caused by penetration of copper atoms into the active area of the devices. The research proved that heating the stack to a high temperature (up to 700 C) produces a sevenfold increase in adhesion. Since the molecules are trapped between the two surfaces, the heating stabilizes the molecular layer, producing the desired result, and creating adhesion on every one of its sides through strong chemical bonds. The improved bond using layers of these dimensions is a scientific innovation, which was developed with support for three years by the US-Israel Binational Science Foundation. REAL-TIME WATER POLLUTION MONITOR Fighting groundwater pollution is critically important to many activities, including those associated with agriculture, forestry, hydrology, pollution abatement and engineering. Now, a simple, fast and cost-effective monitoring system that provides data in real time on the transport of water and contaminates above the level of ground water (known as the vadose zone) has been developed by researchers at Ben-Gurion University in Beersheba. The Water & Contaminants Monitoring System (W&CMS) was developed by Dr. Ofer Dahan, a researcher at the Zuckerberg Institute for Water Research (ZIWR) at BGU's Jacob Blaustein Institutes for Desert Research, and was made public as part of the institute's recent 30th anniversary celebrations. The vadose zone includes the upper soil and rock layers that lies between the land surface and the aquifer water table beneath. Both water and contaminants must pass through the vadose zone prior to entering the water aquifer. Dahan says most sources of man-made pollution originate on land surface right above the vadose zone, including industry, intensive agriculture, landfills and waste lagoons. Unfortunately, vadose zones are not hydraulically isolated - and as a result, water and contaminants may rapidly migrate downward toward the water table and pollute the groundwater. There is evidence that even the thickest vadose zones have limited effectiveness as a filter against contaminants. Monitoring programs for ground water protection were long based on information pulled from groundwater; this monitoring method is well-established around the world, and there are even laws in several countries requiring this type of groundwater monitoring for potential polluters. But the method is flawed, as penetration into the groundwater for monitoring could cause irreversible damage, and the cleaning of contaminated ground water is complicated and very costly. Moreover, this could not provide any protection to groundwater since identification of contamination means by definition it is too late to protect the groundwater. The newly developed BGU system is designed to provide continuous measurements of soil water content and potential in the vadose zones. "The W&CMS has been successfully installed in several places in Israel and other countries, where it has demonstrated that it can enhance the overall protection of the environment," explains Dahan, "by providing earlier and better control of downward water flow and contaminant migration." The availability of the W&CMS system will give governments as well as environmental protection organizations more power to demand that potential polluters stay within guidelines and better protect the quality of water and, as a result, the quality of life, Dahan concludes. ISRAELI SCIENTISTS MOURN DE GENNES The recent death at 74 in Paris of Prof. Pierre-Gilles de Gennes, Nobel Prize laureate in physics, was noted with sadness in Israel. De Gennes had many close affiliations with Israeli physicists, and himself received both the Technion's Harvey Prize and the Wolf Prize for his outstanding work. He received his Nobel 1991 for studying the boundary lines between order and disorder in liquid crystals, polymers and other materials. More than a century after they were discovered, liquid crystals are now widely utilized in flat-screen computer monitors and TVs. Although de Gennes - who was regarded as one of the greatest scientists of the late 20th century - did not invent or construct liquid crystal displays (LCDs), he did discover how they function and behave. But even after winning the Nobel Prize, he remained modest. He went to scores of high schools to talk about science and, thanks to TV appearances to explain science, he was recognized by Frenchmen on the street. In a short speech at the dinner for Nobel Prize recipients, he said: "This is the first and probably the last time in my life where I have dinner with queens and princesses. I am worried. I suspect that with the chimes of midnight I will be turned into a pumpkin."