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Searching for Superhard Materials
July 11, 1998 | Volume 154 |
Number 2
Cover: In computer models, carbon (red) and nitrogen (blue)
atoms easily bond to form b -C3N4, a
material predicted to rival the hardness of diamond. In real life, however, this superhard
material has been super hard to make—prompting scientists to wonder whether it can
exist at all. (Image: Michel Côté, U.C. Berkeley)
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News of the Week:
Parental Care Seen in Mountain Plants
Decaying debris of two species
that flower once and then die provide vital moisture that helps seedlings survive.
Marijuana chemical tapped to fight strokes
Studies
of rat neurons show that a compound in marijuana acts as an antioxidant and might protect
against damage from strokes.
Explosive stripping of a material's surface
Intense,
ultrashort laser pulses transform a thin layer at a solid's surface into a rapidly
expanding, transparent fluid.
Cloned cows provide company for Dolly
The birth of two calves cloned
from adult cells, reported in Japan, provides confirmation of the procedure that created
the cloned sheep called Dolly.
Astronomers find long-period planet
A
newly discovered planet orbiting a nearby star has the lengthiest orbit of any confirmed
extrasolar planet and may be a promising candidate for direct imaging.
Ancient fire use flickers inside cave
A
scientific team found no direct evidence of intentional burning in a Chinese cave widely
regarded as exhibiting the oldest known example of the controlled use of fire.
What’s in ocean water? Shards of bacteria
The
tattered remnants of bacteria constitute much of the dissolved organic matter in the open
ocean.
Tiny icicles grow in electric fields
A
strong electric field forces ice crystals to grow into long, sharp needles rather than
snowflake patterns.
Behavior
A brain area to count on
Discerning
the larger of two numbers elicits electric activity in a specific part of the brain in
both children and adults.
Traumatic rider to mental illness
Astronomers
have discovered a new class of celestial objects, roughly one-third the temperature of the
sun and less than one-tenth its mass.
Biology
Chickadees sneak up the social ladder
DNA
tests of paternity in chickadees show the benefits of surreptitious partnering.
Looking for life in all the worst places
Researchers
find complex microbial communities in one of the coldest spots on Earth—inside the
permanent ice on Antarctic lakes.
Plummeting falcons stay in control
New
measurements help elucidate how gyrfalcons can plunge more than a quarter of a mile out of
the sky without crashing.
Biomedicine
AIDS vaccine trial gets go-ahead
The
U.S. Food and Drug Administration has approved the first large test of a vaccine designed
to prevent AIDS.
Gene therapy for arthritis works in rats
Transplanting DNA that encodes anti-inflammatory
proteins combats arthritis in laboratory rats.
Earth Science
What was life’s first sunblock?
Tarlike polymers in the early oceans may have prevented
ultraviolet light from destroying the first nucleic acids and amino acids.
Signs of unstable ice in Antarctica
The ice covering West Antarctica melted then reformed in
the recent geologic past, raising concerns about its future stability.
Timely Surprises
Biological clocks sense light in obscure ways
New studies identify proteins that may help the human internal biological
clock detect light.
As Hard as Diamond?
Tracking the elusive carbon nitride
Researchers are using a variety of techniques to identify and
synthesize superhard materials.
Letters: A Selection from Letters to the Editor
