By September 10, 2004
Cornell research to be published today in the Journal of Science features a new engineering technique that allows the synthesis of unprecedented small nanostructures using self-assembling macromolecules. Inspired by the self-assembly of organic structures such as animal cell membranes from simpler organic compounds, the technique requires only the synthesis of the macromolecule polymers as well as a controlled increase in temperature to produce a variety of minute structures ranging from tiny conducting cylinders to rigid polygonal structures. The research, compiled by a team led by Prof. Ulrich Wiessner, materials science & engineering, is expected to be applicable to various engineering industries. In particular, “self-assembly is now being discussed in the framework of the microelectronics industry, which will hit a wall in about 10 years in terms of miniaturizing even further,” Wiessner said. The procedure offers the industry an alternative to the traditional top-down approach, in which nanostructures are assembled from large objects through miniaturization. Instead, “you can use bottom-up approaches,” Wiessner added. In addition, many of the final structures produced by the self-assembling molecules have portions that are highly conductive and sections that are effective insulators. Consequently, according to Wiessner, these structures are particularly useful in a variety of devices such as solar cells. The technique begins with the synthesis of a large macromolecule, or polymer, that is comprised of a linear molecule and a tree-like molecule. The linear molecule is extremely hydrophyllic, meaning it readily dissolves in water, while the tree-like molecule is quite hydrophobic. The combination of the two is then heated. “When you heat the material up, [it] changes structure,” Wiessner explained. Basically, “all parts that like water come in contact, and all parts that dislike water come in contact.” The shape of the final structure is highly dependent on temperature and is usually only a few nanometers — a millionth of a centimeter — in width. Consequently, the structures “can be utilized as an on/off switch,” explained Prof. Byoung-Ki Cho, material science and engineering, who synthesized many of the tree-like polymer portions and also participated in much of the research. In essence “this on/off switch can be [controlled] through the temperature,” Cho added. Since much of this research was inspired by similar processes that occur in nature, the self-assembling polymers are essentially organic compounds consisting mainly of carbon, nitrogen, oxygen and hydrogen. “Every living organism is full of self-assembled material,” Wiessner explained, “For example, through a spontaneous process, the cell walls of blood cells are formed — A wonderful example in which self-assembly takes place every day a million times.” Synthesized nanodevices, however, are not yet stable enough to be used in most engineering applications. For instance, in most circuit devices components need to retain their structure and conductivity over a wide range of temperatures and humidity levels. Because most nanostructures created using this process change form readily with small changes in temperature, this is not guaranteed. “We are currently optimizing the material, the structure, the conductivity value … [as well as] broadening the temperature,” Cho said. Other areas of future research include the integration of non-organic molecules into the self-assembling polymer structure as well as reforming the macromolecule’s structure itself. For instance, Cho plans to test new polymer structures that vary from the current polar setup with the linear portion on one end and the treelike structure on the other end. “He is extending [the structure] to an ABA kind of system, with a linear chain in in the middle and the [tree-like] structure on both sides,” said Surbhi Mahajan grad, who synthesized most of the linear portions and also contributed to the research. The paper will appear in today’s issue of Science and received funding from the National Science Foundation. Other contributors to the research included Anurag Jain.Archived article by David Andrade Sun Staff Writer
By September 10, 2004
The Ithaca Common Council and the Ithaca Dispatch taxi service raised taxi cab prices last July. The increase in cab fares is due to the rise in gas prices this year. Taxi fares were raised by at least 25 cents, resulting in charges of $4.85 during the day and $5.85 at night. The exact cost of a ride depends on the time of day, location and number of passengers. John Kadar, owner of Ithaca Dispatch, worked with Ithaca Common Council members to plan the rise in the taxi cab prices. “Effective as of this past July, the daytime and nighttime prices for a taxi ride were raised by one quarter per ride for each taxi zone,” Kadar said. There was an additional 50-cent surcharge between the hours of midnight and 5 a.m. before the ordinance was passed. “Now, the nighttime surcharge schedule has been changed, beginning at 8 p.m. instead of midnight,” Kadar said. At 8 p.m., there will now be a 50-cent surcharge added. Cab rides will charge one extra dollar per passenger for trips taken after 8 p.m. If one person rides after 8 p.m., there is no surcharge. Each additional person will be charged one extra dollar to ride. These increases are effective until Dec. 31, 2004. “The increase is only temporary,” Kadar said. “The emergency increase in cab fares was due to the rapid increase in the gas prices recently. We requested the fare to go up, but if the gas prices go down beyond a certain level, we will re-settle the fares at the end of the year,” Kadar explained. The rise in cab fares affects every taxi company in Ithaca. The rates are set by the Common Council by the city of Ithaca. “Ithaca Dispatch controls three taxi services: University Taxi, Cayuga Taxi and Yellow Cab of Ithaca. Other taxi companies will also be affected by the Common Council’s decision to raise the fares,” said Kadar. Common Council member Michael Taylor (D-4th Ward) said, “The biggest change occurred in the premium charge for evening rides because of the skyrocketing gas prices.” “Our theory is that people who take cabs during the day are more likely to be engaged in rides of necessity. The nighttime riders are people who are headed to the movies, the mall or to a party,” Taylor said. “If we increased the fares for nighttime passengers using cabs for recreational use, it would be a more fair and just system,” said Taylor. Taylor is concerned that nighttime riders may choose not to take a ride if the prices become a problem. He expressed concern specifically for female riders who may need to get home safely. “I feel there are certain circumstances where we don’t want to discourage cab use. If you are out at night by yourself and you need to get back to your dorm, hopefully the increase in the cab fares will not compromise your own personal safety,” said Taylor. Some students have been directly affected by the increase in fares already. Elana Fisher ’07 has been taking less taxi cab rides into Collegetown since the increase in cab fares. “We are college students living on a fixed budget. If the cab prices keep going up, I’ll just have to catch a ride from the Wings Over Ithaca delivery guy,” Fisher said. “Hopefully the prices go down before winter comes around because walking from my house to Collegetown can be very long and tiresome.” “I guess this just shows the law of supply and demand. If they can get people to pay the price, why not raise it?” questioned Alon Mass ’08. “If it gets us home safe, it’s worth the extra money.” “Right now, I’d rather just walk home and not have to spend the money,” Mass said. “I might try the taxis when it gets colder out.” Archived article by Allison MarkowitzSun Staff Writer