Researchers Produce First Clear Look at Sunspot Core
Analysis of sounds waves inside the sun has provided a Stanford-based research team with a detailed image of the inner core of a sunspot. The first observation of the actual dynamics of sunspots just below the visible surface, the study sheds light on the origin of the planet-sized dark solar regions.
Findings reveal fast-moving, downward streams of hot plasma - flows of electrically charged gas - converging into a gigantic vortex that penetrates the surface of the sun. The plasma flows travel toward the interior of the sun at speeds of about 3,000 miles per hour, and create a self-reinforcing cycle that holds the region together.
To chart the interior of the sunspot, researchers used data obtained from the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO) - a research satellite positioned approximately one million miles from Earth. Using a technique known as helioseismology, the MDI maps the solar interior by measuring the velocity of sound waves passing through the sun.
Sunspots, which are active magnetic regions often accompanied by powerful solar storms, can disrupt radio communications, power grids, and orbiting satellites.
- Nancy L. Keuss
Carbon Nanotubules Channel Water Despite Hydrophobic Core
Researchers at the National Institutes of Health and the University of Maine have determined that water molecules can enter the hydrophobic core of carbon nanotubules. Through the use of relatively long-scale computer simulations, this research could lead to a fundamental understanding of biological pore mechanisms.
As reported in the journal Nature, when the strengths of van der Waals’ interactions between water molecules and the carbon atoms constituting the tube are compared, it is energetically favorable for the tubules to accommodate five-molecule, single-file columns of water.
Furthermore, researchers write, “we observe pulse-like transmission of water through the nanotube. These transmission bursts result from the tight hydrogen-bonding network inside the tube, which ensures that density fluctuations in the surrounding bath lead to concerted and rapid motion along the tube axis.”
The interaction is unstable, however, as conditions are slightly less than favorable. The water molecules rarely enter the cavity of the nanotubule. Research shows that a reduction of the interaction’s energy well from -0.114 kcal/mol to -0.065 kcal/mol renders the tube pore virtually free of any water molecules.
The work is relevant not only to the booming field of carbon nanotubule research, which has generated considerable excitement over its electrical properties, but also to further molecular dynamics studies of other water-filled pores of similar size, such as membrane-spanning ion-channel proteins and aquaporins.
- Shankar Mukherji
Operation Marks Fifth Artificial Heart Implant
A Philadelphia patient is the world’s fifth recipient of a self-contained artificial AbioCor heart.
Dr. Louis E. Samuels of the Hahnermann University Hospital, who performed the operation on Monday, said that the plastic-and-titanium heart was performing flawlessly, though the patient was experiencing pulmonary distress requiring external oxygenation support.
The AbioCor device is for critically ill heart patients -- people whose hearts are destroyed, which includes 50,000-70,000 Americans annually. A completely internal device, the AbioCor comes with a pack of rechargeable batteries about the size of a VCR tape which are worn about the waist. These power the heart by transmitting current through the skin without wires. The battery can be recharged by plugging it into an AC outlet, which gives the patient freedom to move about.
The self-contained mechanical hearts, implanted in five patients thus far, are made by Danvers, Massachusetts-based Abiomed Inc. The U.S. Food and Drug Administration granted permission for five of the devices to be used in initial clinical trials. The first heart recipient underwent the operation on July 2, and is reported to be doing well.
- Nancy L. Keuss