NEWS OF THE WEEK PHYSICS
TABLETOP NUCLEAR FUSION DEVICE Electric-field-generating crystal drives deuterium-deuterium fusion
NEUTRON SOURCE A3-cmdiameter lithium tantalate crystal (bottom)p a pyroelectric material, is key to the neutronemitting "pyrofusion" device.
A
SIMPLE DEVICE THAT FITS
into a lab-coat pocket can be used to achieve deuterium-deuterium fusion along with its associated neutron flux under desktop conditions, according to scientists at the University of California, Los Angeles (Nature 2005, 434,1115). The device is not practical for power generation, but it may find use as a palm-sized neutron generator in the laboratory Unlike magnetic and inertial confinement fusion, the new UCLA system is a tabletop method for producing nuclear fusion,
but it's otherwise not related to the "cold fusion" and "bubble fusion" claims of recent years that have met with deep skepticism. The physics behind it is conventional and accepted, says lead author Brian Naranjo, of physicist SethJ. Puttermaris group, which is collaborating with chemist James K. Gimzewski. The apparatus they used consists of a chamber containing a lithium tantalate (LiTaO^ crystal and an erbium deuteride (ErD^ target in a low-pressure atmosphere of deuterium. W h e n the crystal is gently warmed, it gen-
BIOETHICS
ETHICAL STEM CELL RESEARCH Academies provide guidance for work largely unregulated by federal government GUIDANCE Moreno (left) and fellow report cochair Richard 0. HyneSp biology professor and Howard Hughes Medical Institute investigator at MIT, discuss the new guidelines.
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C & E N / MAY 2, 2 0 0 5
T
O HELP STANDARDIZE AND
protect the integrity of human embryonic stem cell (hESC) research, the National Academies has prepared a 131page report containing a set of nonbinding ethics guidelines for scientists working in this area. Topping the list of recommendations
is the call for institutions doing hESC research to set up oversight committees-withmembersfrom the public and scientific community—to review and monitor all hESC research proposals. "Heightened oversight is essential to assure the public that stem cell research is being carried out in an ethical manner," said report cochairJonathan D. Moreno, biomedical ethics professor at the University of Virginia. "The oversight we call for will in many instances set a higher standard than required by existing laws or regulations." The guidelines include a tightening of rules governing the donation of embryos, eggs, and sperm. The report recommends
erates an electric field that is concentrated at the tip of a tungsten needle attached to the crystal. At the tip, the D 2 molecules become ionized and the D + ions are accelerated toward the ErD 2 target, where D + D fusion occurs, producing helium-3 and a 2.45-MeV neutron, a signature of D + D fusion. About 9 0 0 neutrons per second are produced—400 times the usual background level. By enhancing the system and using a tritiated target, the researchers expect to boost the flux beyond 1 million neutrons per second. Even at the flux already attained, a simple, inexpensive, single-energy neutron source like this one would be desirable for lab applications such as measuring the response of neutron detectors or for student demonstrations, notes physicist Michael J. Saltmarsh of Oak Ridge National Laboratory—RON DAGANI
that all donors be required to give informed consent, that all research using such donations be reviewed by institutional review boards, and that donors not be paid for their donation. In addition, the report warns against combining hESC with nonhuman primate embryos. For other, nonprimate animals, such as mice, introduction of hESC should be allowed after careful review, and the resulting hybrids should not be allowed to breed, the report says. "This report is absolutely critical to ensure an effective and ethical approach to embryonic stem cell research," said Rep. Michael N. Castle (R-Del.). Castle is a cosponsor of a House bill to increase the number of hESC lines available for study with federal funds. "By ensuring that this cutting-edge research adheres to the highest ethical standards, the {National Academies] is rightly providing strong oversight recommendation," he said.—SUSAN M0RRISSEY
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