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Deconstructing superconductors. Using a scanning tunneling microscope with a resolution of a 10th of an angstrom (an angstrom is one 10,000 millionth of a meter), BU physicists Shuheng Pan, a CAS associate professor, and Claudio Chamon, a CAS assistant professor, and a team of colleagues from across the United States and in Japan have revealed an important physical property of high-temperature superconductors -- materials that have virtually no resistance to electricity. The team found an inhomogeneity in the electronic structure that may prove to be important to its superconducting behavior.

Superconducting materials were first discovered in 1911 by H. Kamerlingh Onnes, who noticed that a frozen rod of mercury cooled to a temperature of about minus 450 degrees Fahrenheit offered no resistance to electricity. In the 1950s it was found that these superconductors use pairs of electrons to carry electrical current. As the first electron of the pair passes through the crystal lattice structure of the superconductor, it creates a slight distortion that in effect attracts the second electron to move along. The physicists responsible for both of these discoveries were awarded Nobel prizes.

In the mid-1980s two IBM researchers, George Bednorz and Alex Müller, discovered a ceramic material that acts as a superconductor at significantly higher temperatures -- about minus 397 degrees Fahrenheit -- a discovery that led to a third Nobel prize. Soon after, the temperature was pushed to minus 209 degrees Fahrenheit.

The subject of Pan's investigations, a copper oxide ceramic insulator, is doped, or enriched, with excess oxygen atoms to transform it into a superconductor. It is known that the additional oxygen atoms are responsible for the superconducting properties, but after 15 years of research, the transition still remains a mystery. Many models have tried to explain it, all assuming that the material is electronically homogeneous. Pan's research revealed that on the contrary, these materials are intrinsically inhomogeneous.

Chamon points out that the discovery raises important questions. Does the disordered arrangement enhance or detract from superconductivity? Can control of the disorder be used to further enhance superconductivity? Answering these questions may lead to new superconducting materials that operate at higher temperatures -- perhaps even at room temperature. Such materials have important potential applications in particle accelerators and in consumer technologies such as MRIs and new electromagnetically based high-speed trains, boats, automobiles, and elevators.

This research was reported in the September 20 Nature.

Surgically stressed. Surgery is a stressful experience, but patients typically recover without suffering from post-traumatic stress disorder (PTSD). This does not seem to be true for a small percentage of patients who experience an anesthetic failure resulting in awareness during surgery.

"Most post surgery awareness subjects reported lapsing in and out of consciousness, picking up fragments of the surgery, conversations, and bodily sensations while struggling to move, escape, and communicate," says Janet E. Osterman, assistant professor of psychiatry at the BU School of Medicine and author of a recent study on the subject. "These memories later reappear as vivid images, sensations, isolated thoughts, and the intense emotions characteristic of PTSD."

Subjects taking part in Osterman's study reported an inability to communicate during their surgery, pain, fear of pain, paralysis, and feeling unsafe, as well as intense feelings of helplessness and terror. They further reported feeling abandoned or betrayed by their doctors and nurses. These feelings persisted well after surgery.

Other patients in the study described themselves as "the living dead," or "zombies," exhibiting dissociation -- a feeling of being disconnected from their bodies. According to the study, these patients may appear calm and unaffected by the traumatic event, and thus unlikely to be identified by caregivers as having suffered a traumatic awareness experience.

"Awareness-induced PTSD is especially problematic, because these people will often avoid doctors and hospitals so as not to be reminded of the traumatic experience," says Osterman. She notes that postoperative patients should be assessed for awareness under anesthesia and provided with therapeutic interventions including validation and support from the surgical and anesthesia team, and if needed, treatment for PTSD.

Osterman's study was partially funded by Aspect Medical Center, Inc., of Natick, Mass., and appeared in the July-August issue of General Hospital Psychiatry.

"Research Briefs" is written by Joan Schwartz in the Office of the Provost. To read more about BU research, visit http://www.bu.edu/research.

21 September 2001
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