SCIENCE IN THE NEWS in VOA Special English.
I'm Barbara Klein.
Steve Ember. This week, we will tell
about an American study of the brain disorder schizophrenia. We tell about cars that use hydrogen as
fuel. And, we will tell how one kind of
tree deals with threats to its existence.
who are schizophrenic sometimes hear voices or see things that are not
real. They might believe other people
want to hurt them. They can become
fearful and socially withdrawn.
National Institute of Mental Health describes schizophrenia as a brain disorder
that is severe and disabling. It is
also chronic, meaning long term.
disorder usually appears in young men in their late teens or early twenties and
in women in their twenties or thirties.
Experts say it rarely appears in children. But when it does, it generally affects them more severely than
with schizophrenia are often treated with "second-generation"
antipsychotic drugs. But do these
costly newer drugs work better than older ones that cost less? The National Institute of Mental Health
recently paid for a study by four universities in the United States. The research teams found that the answer was
studied one hundred nineteen people between the ages of eight and
nineteen. The patients were observed
over an eight-week period. Some
received two newer drugs: risperidone or olanzapine. Others received a first-generation antipsychotic drug, molindone.
study found that all of the patients experienced about the same
improvement. But the risperidone and
olanzapine caused serious weight gain.
In fact, the institute cancelled the olanzapine research because the
patients who took it gained an average of almost six kilograms. The concern was that the weight gain could
lead to diabetes.
years, the automobile industry has been testing vehicles that use hydrogen as
fuel. Now, people across the United
States have had a chance to see and even drive cars that get power from
hydrogen fuel cells.
event was called Hydrogen Road Tour Oh-Eight.
It took place earlier this year in thirty-one American cities. The road tour started in Maine and ended in
southern California on August twenty-third.
carmakers, two federal agencies and two other groups helped organize the
event. It gave people interested in new
technologies a chance to possibly experience the future of transportation.
the tour's stop in Washington, D.C., several hundred people gathered to test
drive hydrogen powered cars. The cars
look like other vehicles driven by millions of Americans everyday. But it is hydrogen, not more traditional
fuels, that provides power for the cars.
fuel cells represent huge steps forward in technology. But the hydrogen fuel cell is not a new
idea. The fuel cell was invented by Sir
William Grove of Britain in eighteen thirty-nine. Since then, many different designs have been invented.
one place where fuel cells are a proven technology: in space. The American space agency used fuel cells in
its Apollo spaceships in the twentieth century. And fuel cells provide all the electrical power for space
useful fuel cell for transportation purposes is the Polymer Electrolyte
Membrane, or P.E.M., fuel cell. It is
simple and can operate at temperatures of sixty to eighty degrees Celsius. That is much lower than other fuel cell
fuel cell has two sides separated by a thin substance or membrane. Hydrogen gas is forced through one side
where it comes in contact with a reactive material containing the metal
membrane separates the electrons from the protons in the hydrogen atoms. The protons pass through it to the other
side of the fuel cell. But the
electrons are captured to do work: like powering a motor.
from the air is forced into the other side of the fuel cell. There, the gas meets the protons that have
passed through the membrane. They
combine to form water and heat.
fuel cell does not produce a lot of electricity. But when many fuel cells are combined, they can produce enough
electricity to power a vehicle. The
product of the chemical reaction that powers fuel cells is water. This makes fuel cells a very clean
cell cars have been slow to develop because of many technical problems that
have to be solved. For example, it is
unclear how long the membranes in P.E.M. fuel cells will last.
fuel cells need water for their chemical reactions. They must be designed to start easily in low temperatures and in
dry climates. And smaller, less costly
fuel cells must be designed before they can truly replace gasoline engines.
Hydrogen Road Tour Oh-Eight has shown the progress carmakers have made. BMW, Daimler, Ford, General Motors and Honda
took part in the event. Also included
were Hyundai-Kia, Nissan, Toyota and Volkswagen. Most of these companies already have hydrogen-powered models that
are in use on roads today.
more models of fuel cell vehicles being tested than ever before. The threat of climate change and the high
cost of oil has increased interest in these vehicles that do not cause
pollution. But car buyers should not
expect to see fuel cell cars at their local dealer any time soon. Automakers say they will not build many fuel
cell cars until hydrogen fueling and service stations are widely
available. And that will cost billions
of dollars and years of effort.
American scientists have discovered that walnut trees can produce more than
walnuts. The scientists say walnut
trees also can make a chemical form of the popular pain-killing medicine
aspirin. The trees do this under the
stress, or pressure, of disease or other threats. Scientists say the chemical may help the trees reduce damage from
dry weather, unseasonable temperatures and other changes in the
Karl reported the discovery. He works
for the National Center for Atmospheric Research, NCAR, in Boulder,
Colorado. The National Science
Foundation paid for the study. The
results appeared recently in the publication Biogeosciences.
results are important because presence of the chemical could warn growers early
that a tree is in danger. Growers could
recognize a problem before leaves on walnut trees die and fall off. The scientists said the findings also show
that a plant can communicate with other plants through the atmosphere. For example, a tree could communicate when
it is under attack from insects. With
that information, a grower could begin corrective treatment.
have known for a long time that laboratory plants may produce methyl
salicylate, aspirin's chemical form.
Aspirin was first produced from the bark covering on willow trees. But the researchers had never before found
methyl salicylate in a forest. They had
not confirmed that trees could emit, or release, large amounts of the chemical
into the atmosphere.
American scientists discovered the chemical by accident. It happened after the NCAR team placed
special measuring equipment in an area of walnut trees near Davis,
California. The equipment was placed on
structures about thirty meters above ground.
of the team was to observe some chemicals called volatile organic compounds, or
VOCs, that the trees emit. The organic
compounds can influence climate and affect pollution. Mister Karl and his team were surprised to find that the
emissions of the VOCs contained methyl salicylate.
scientists said a long period without rain had already affected the trees. Then the stress increased. Leaf temperatures dropped to as low as about
four and six-tenths degrees Celsius during the night. The cool conditions especially affected the trees when
temperatures climbed quickly in the morning.
The team said the change in temperature probably made the walnut tree
react. The tree apparently attempted to
prevent freezing by emitting the chemical form of aspirin.
SCIENCE IN THE NEWS was written by Mario Ritter, Jerilyn Watson and Caty
Weaver. Our producer was Brianna
Blake. I'm Barbara Klein.
Steve Ember. You can read and
listen to our programs at voaspecialenglish.com. Join us
next week for more news about science in VOA Special English.