Black Hole Does Lunch

Black holes are super-dense heavenly bodies whose gravitational pull is so intense even light can’t escape once it passes a theoretical boundary called an event horizon. Scientists are virtually certain a black hole exists at the center of our own Milky Way galaxy, and an MIT-led group has now reported evidence of matter disappearing into this mysterious entity. The tip-off was a massive X-ray flare that came from near the presumed location of this unusual Milky Way inhabitant but outside its event horizon. X-ray levels from the source jumped dramatically, and in about three hours declined to pre-flare levels. Frederick Baganoff, the MIT Center for Space Research scientist heading the research team, says the flare almost certainly reflects the death throes of a comet-sized chunk of matter being swallowed by the black hole. At the peak of the flare, the team –– which also included members from Penn State and UCLA along with a Japanese group –– found that the X-rays’ intensity dropped by a factor of five over a 10-minute span, indicating the rays were emitted by hot matter moments before it plunged into the black hole’s event horizon. “This is the first time we’ve seen a super-massive black hole devour a chunk of material in our own neighborhood,” adds Baganoff.

Aid For Surgeons

Operations done through tiny incisions –– an approach called keyhole surgery –– are popular with surgeons and patients alike. But problems suturing tissues in the body through these minimal openings have seriously impeded wider use of the technique. Now leading MIT biological engineer Robert Langer and a collaborator from Germany may have overcome that barrier. Their solution: a new class of biodegradable plastics that change shape in response to selected cues, like a boost in temperature. The materials are made of two types of components that vary in their responses to heat. As a result, they can be put in place in one configuration and can quickly adopt another. The plastics –– first of their kind to be developed –– open the door for applications like “self-tightening” sutures. “We created an elongated fiber that was used to loosely close off a wound on a rat,” notes Langer, a professor of chemical and biological engineering. When the temperature of the material was raised, it tightened the knot to just the right degree of tension without further human intervention. The materials, which Langer created with Andreas Lendlein of the University of Technology in Aachen, Germany, could also yield other products –– for example, biodegradable versions of the devices called stents that would keep recently widened blood vessels open long enough for these passageways to heal. Lendlein, a former visiting scientist at MIT, has launched a company to manufacture and market devices made from the innovative materials.

Easier Electricity

The fact that heat applied to certain types of paired materials yields an electric current underlies the make-up of an array of devices. Among them are thermocouple temperature measuring instruments, whose critical components are two types of metals. For over a century engineers and scientists have tried to exploit the current-generating qualities of materials so as to produce electricity from heat, too, but with limited success. The applications that have paid off so far are those where special circumstances, like the need to provide power on a satellite, overcome the inefficiencies and other downsides of traditional thermoelectric systems. But now an MIT scientist and a colleague report that some key modifications to so-called solidstate versions of these devices may lead to systems more versatile and cost-effective than present-day variants. MIT’s Peter Hagelsteinand Yan Kucherov of Utah-based Eneco, Inc., say that by making subtle but critical changes to the internal makeup of a solid state device –– which vaguely resembles an unusually large computer chip, and like a chip is largely composed of semiconducting materials –– you can markedly boost its operating efficiencies. Importantly, such a system could also work with heat-input temperatures between 200 and 450 C. That means it could be used, for one example, to augment your car’s electrical output by harnessing waste heat. Hagelstein, an associate professor of electrical engineering and computer science, notes that the proposed devices have another advantage, too: “The process generates no pollution.”

Tumor Connection

For the first time, scientists have linked a form of cancer to a problem with the body’s system for translating the information encoded in our genes into new proteins. At the core of this system is the genetic messenger, dubbed mRNA. Unlike its close cousin, DNA, this molecule’s main job is to convey genetic information from a cell’s nucleus –– where our DNA resides –– to its in-house protein factories. There, the RNA-borne information is used as a blueprint for building all kinds of proteins. But the information doesn’t always come out exactly right, and MIT’s Alexander Rich believes that fact may explain at least some aspects of the deadly brain cancer called glioma multiforme. Rich, a professor of biology, Stefan Maas, a research scientist, and their colleagues from Friedrich Schiller University in Germany, say their work shows that the failure of the RNA to undergo appropriate “editing” before it conveys its message –– a normal feature of the RNA-based system for conveying information within cells –– may be at fault. The resulting abnormal protein, the group found, leads to channels in and out of brain cells that work much differently from their normal counterparts. Although the defect probably doesn’t cause the cancer, says Rich, “the symptoms of gliomas may be related to this.” Among those symptoms are the severe seizures that afflict many glioma patients.