Is It Possible To
Maneuver Around A
Laser Beam Alarm?
Finding: BUSTED
Explanation: The MythBusters took on spy movie magic and attempted to pull off a
modern-day heist masterminded by Grant Imahara. Since every good Hollywood heist
involves outwitting alarm systems, Grant constructed a laser beam alarm room outfitted
with visible and infrared lasers for Tory Belleci and Kari Byron to try to tiptoe their way
through.
Setting up the laser beam alarm system was easier said than done, however, since no
known alarm companies actually manufacture systems with visible laser beams like we
see in the movies. Why? Because, as amateur thieves Tory and Kari proved with this
experiment, it may be possible to worm your way around the visible lasers. For example,
they found that blowing fine powder in the air, a la Catherine Zeta Jones in the film
Entrapment, could illuminate the rays, and jamming another laser into the alarm laser
receptor might disarm the system.
In reality, though, most security system companies use infrared laser beams, which are
invisible. So while Tory and Kari could plausibly tiptoe around the visible laser beams,
the infrared laser backup system - the one today's tricksters are up against — busted them
every time.
As seen in "MythBusters: Crimes and Myth-Demeanors."
Can You Stop A Car
By Shifting It Into
Reverse?
Finding: BUSTED
Explanation: In the 1930s, comic book character Dick Tracy had a hair-raising ride in a
brake-tampered car, though he didn't even try to shift gears to stop it, as this myth
suggests. But could you really stop a speeding car by shifting into reverse? The
MythBusters got behind the wheel to put the brakes on this tire-squealing myth.
Two types of transmissions — manual and automatic — are at the center of this theory,
but neither offers much stopping power when you're commandeering a steel bullet on
wheels. Turns out, you can put a moving car's automatic shifter into reverse, but the
transmission will actually go into neutral. Most modern vehicles have safeguards to
prevent engine damage, which is what would happen if you flipped directly from "D" to
"R." Putting it in neutral will keep your vehicle from continuing to accelerate as if you
were pressing the gas pedal, but unless you're also applying the brakes, the change in
gears alone won't slow your current speed drastically enough to stop it.
If you discover your brakes don't work, downshifting a manual transmission into a lower
gear can slow your speed. But when the car is moving, the reverse gear won't work
because it turns in a direction opposite to all the other gears.
Looks like when the brakes are out, your only option besides "go" is "slow."
As seen in "MythBusters: Viewer Special I."
Can A Secret Agent
Dive To A Formal
Party In A Tuxedo?
Finding: CONFIRMED
Explanation: How many times has James Bond or some other big-screen spy hopped
into a tuxedo, taken a scuba dive and then arrived at a cocktail party looking fresh as a
daisy? Enough times for a viewer to ask MythBusters Jamie Hyneman and Adam Savage
to test whether the confines of a scuba suit can really keep a tux looking crisp and dry.
For the sake of science, Jamie first slipped on a penguin suit and then zipped into a dry
suit. Astonishingly, after he emerged from his scuba dive and removed his underwater
apparel, the tuxedo didn't bear a single water droplet or wrinkle.
Although a lot of spy movie antics are impossible to pull off, the MythBusters confirmed
that you can indeed scuba dive to a black tie event without mussing up the tux.
As seen in "MythBusters: Minimyth Madness"
Can You Beat Police
Radars?
Finding: BUSTED
Explanation: One of the most feared weapons in a police officer's arsenal is the dreaded
radar gun. By firing at passing cars with microwaves that then bounce back at different
frequencies, the devices detect whether drivers are cruising over the speed limit.
MythBusters Tory Belleci, Kari Byron and Scottie Chapman tried out a lineup of
supposed radar gun-dodging tricks, including jingling keys at the radar gun; hanging
disco balls and CDs from rearview mirrors; installing LED light license plates; and
covering hubcaps and an entire car in aluminum foil. The team also assembled a
microwave gun and aluminum foil-shooting gun meant to scramble the police radar
gadgets. As a last resort, the MythBusters even covered their test Cadillac in matte black
paint in hopes of sneaking it past the radar undetected.
But as the MythBusters suspected, none of these stealth tactics helped them give the radar
gun the slip.
Let the busted myth be a lesson to lead-footed folks everywhere — the only surefire way
to pass by police speed guns without getting caught is to drive the speed limit.
As seen in "MythBusters: Beat the Radar Detector"
Environmental Scientist
Have you ever noticed that for people with asthma it can sometimes be especially hard to
breathe in the middle of a busy city? One reason for this is the exhaust from vehicles.
Cars, buses, and motorcycles add pollution to our air, which affects our health. But can
pollution impact more than our health? Cutting down trees, or deforestation, can
contribute to erosion, which carries off valuable topsoil. But can erosion alter more than
the condition of the soil? How does an oil spill harm fish and aquatic plants? How does a
population of animals interact with its environment? These are questions that
environmental scientists study and try to find answers to. They conduct research or
perform investigations to identify and eliminate the sources of pollution or hazards that
damage either the environment or human and animal health. Environmental scientists are
the stewards of our environment and are committed to keeping it safe for future
generations.
Education and Training
A bachelor's degree in an earth science is adequate for entry-level positions, although
many companies prefer to hire environmental scientists with a master's degree in
environmental science or a related natural science. A doctoral degree generally is
necessary only for college teaching and some research positions. Some environmental
scientists and specialists have a degree in environmental science, but many earn degrees
in biology, chemistry, physics, or the geosciences and then apply their education to the
study of the environment. They often need research or work experience related to
environmental science.
A bachelor's degree in environmental science offers an interdisciplinary approach to the
natural sciences, with an emphasis on biology, chemistry, and geology. Undergraduate
environmental science majors typically focus on data analysis and physical geography,
which are particularly useful in studying pollution abatement, water resources, or
ecosystem protection, restoration, and management. Understanding the geochemistry of
inorganic compounds is becoming increasingly important in developing remediation
goals. Students interested in working in the environmental or regulatory fields, either in
environmental consulting firms or for federal or state governments, should take courses
in hydrology, hazardous-waste management, environmental legislation, chemistry, fluid
mechanics, and geologic logging, which is the gathering of geologic data. An
understanding of environmental regulations and government permit issues also is
valuable.
For environmental scientists and specialists who consult, courses in business, finance,
marketing, or economics may be useful. In addition, combining environmental science
training with other disciplines such as engineering or business qualifies these scientists
for the widest range of jobs.
Other Qualifications
Computer skills are essential for prospective environmental scientists. Students who have
some experience with computer modeling, data analysis and integration, digital mapping,
remote sensing, and geographic information systems (GIS) will be the most prepared to
enter the job market.
Environmental scientists and specialists usually work as part of a team with other
scientists, engineers, and technicians, and they must often write technical reports and
research proposals that communicate their research results or ideas to company managers,
regulators, and the public. Environmental health specialists also work closely with the
public, providing and collecting information on public health risks. As a result, strong
oral and written communication skills are essential.
Nature of the Work
Environmental scientists use their knowledge of the natural sciences to protect the
environment by identifying problems and finding solutions that minimize hazards to the
health of the environment and the population. They analyze measurements or
observations of air, food, water, and soil to determine ways to clean and preserve the
environment. Understanding the issues involved in protecting the environment—
degradation, conservation, recycling, and replenishment—is central to the work of
environmental scientists. They often use this understanding to design and monitor waste
disposal sites, preserve water supplies, and reclaim contaminated land and water. They
also draft risk assessments, describing the likely effect of construction and other
environmental changes, write technical proposals, and give presentations to managers and
regulators.
Many environmental scientists work for local, state, and federal governments, ensuring
that environmental regulations are followed to limit the impact of human activity on the
environment. Others monitor environmental impacts on the health of the population,
checking for risks of disease and providing information about health hazards.
Environmental scientists also work with private companies to help them comply with
environmental regulations and policies. They are usually hired by consulting firms to
solve problems.
Many environmental scientists have jobs and training similar to other physical or life
scientists, but they focus on environmental issues. Many specialize in subfields such as
environmental ecology and conservation, environmental chemistry, environmental
biology, or fisheries science. Specialties affect the specific activities that environmental
scientists perform, although recent understandings of the interconnectedness of life
processes have blurred some traditional classifications. For example, environmental
ecologists study the relationships between organisms and their environments and the
effects on both by factors such as population size, pollutants, rainfall, temperature, and
altitude. They may collect, study, and report data on air, soil, and water using their
knowledge of various scientific disciplines. Ecological modelers study ecosystems,
pollution control, and resource management using mathematical modeling, systems
analysis, thermodynamics, and computer techniques. Environmental chemists study the
toxicity of various chemicals—that is, how those chemicals harm plants, animals, and
people.
Work Environment
Many entry-level environmental scientists and specialists spend a significant amount of
time in the field, while experienced workers generally devote more time to office or
laboratory work. Some environmental scientists, such as environmental ecologists and
environmental chemists, often take field trips that involve physical activity.
Environmental scientists in the field may work in warm or cold climates, in all kinds of
weather. Travel often is required to meet with prospective clients.
On the Job
• Collect, synthesize, analyze, manage, and report environmental data, such as pollution
emission measurements, atmospheric monitoring measurements, meteorological
and mineralogical information, and soil or water samples.
• Analyze data to determine validity, quality, and scientific significance, and to interpret
correlations between human activities and environmental effects.
• Communicate scientific and technical information to the public, organizations, or
internal audiences through oral briefings, written documents, workshops,
conferences, training sessions, or public hearings.
• Provide scientific and technical guidance, support, coordination, and oversight to
governmental agencies, environmental programs, industry, or the public.
• Process and review environmental permits, licenses, and related materials.
• Review and implement environmental technical standards, guidelines, policies, and
formal regulations that meet all appropriate requirements.
• Prepare charts or graphs from data samples, providing summary information on the
environmental relevance of the data.
• Determine data collection methods to be employed in research projects and surveys.
• Investigate and report on accidents affecting the environment.
• Research sources of pollution to determine their effects on the environment and to
develop theories or methods of pollution abatement or control.
Companies That Hire Environmental Scientists
• CH2M Hill
• U.S. Federal Government
URS
Ask Questions
Do you have a specific question about a career in Environmental Science that isn't
answered on this page? Post your question on Science Buddies Ask an Expert Forum.
Additional Information
• U.S. Environmental Protection Agency
Sources
• BLS. (2009). Occupational Outlook Handbook (OOH), 2008-09 Edition, Bureau of
Labor Statistics. Retrieved May 1, 2009, from http://www.bls.gov/oco/
• O*Net Online. (2009). National Center for O*Net Development. Retrieved May 1,
2009, from http://online.onetcenter.org/
• Smith, S. E. (2011, February 25). What Does an Environmental Scientist Do?
wiseGEEK.com. Retrieved May 4, 2011, from www.wisegeek.com/what-does-anenvironmental-scientist-do.htm
• The Princeton Review. (n.d.). Environmentalist/environmental scientist. Retrieved May
4, 2011, from www.princetonreview.com/Careers.aspx?cid=61
• Oregon State University. (2011). Interview with Dr. Staci Simonich. Environmental
Health Sciences Center. Retrieved May 4, 2011, from
www.unsolvedmysteries.oregonstate.edu/meet_Staci
• Haroski, D. (n.d.). Science Notebook: Interview with Kathryn Snead. U.S.
Environmental Protection Agency. Retrieved May 4, 2011, from
www.epa.gov/epahome/sciencenb/interviews/snead.html
Twin Cities Public Television. (2006). Real scientists: Ariana Sutton-Grier.
DragonflyTV. Retrieved June 23, 2011, from
pbskids.org/dragonflytv/scientists/scientist56.html
http://www.sciencebuddies.org/science-fair-projects/science-engineeringcareers/EnvSci_environmentalscientist_c001.shtml#whatdotheydo
Researchers fitted some dung beetles with cardboard
caps to keep their eyes on the ground, finding they had
more difficulty navigating a circular arena when their
view of the sky was blocked.
CREDIT: Marcus Byrne
Wow! Dung Beetles
Navigate by the Stars
By: Joseph Castro, LiveScience Contributor
24 January 2013 - Despite having tiny brains, dung beetles are surprisingly decent
navigators; able to follow straight paths as they roll poo balls they've collected away from
a dung source. But it seems the insects' abilities are more remarkable than previously
believed. Like ancient seafarers, dung beetles can navigate using the starry sky and the
glow from the Milky Way, new research shows.
"This is the first time where we see animals using the Milky Way for orientation," said
lead researcher Marie Dacke, a biologist at Lund University in Sweden. "It's also the first
time we see that insects can use the stars."
After locating a fresh pile of feces, dung beetles will often collect and roll away a large
piece of spherical dung. Last year, Dacke and her colleagues discovered the beetles climb
on their dung balls and dance around in circles before taking off. This dance is not one of
joy, however; the insects are checking out the sky to get their bearings.
"The dorsal (upper) parts of the dung beetles' eyes are specialized to be able to analyze
the direction of light polarization — the direction that light vibrates in," Dacke told
LiveScience. So when a beetle looks up, it's taking in the sun, the moon and the pattern of
ambient polarized light. These celestial cues help the beetle avoid accidentally circling
back to the poo pile, where other beetles may try to steal its food, Dacke said.
In addition to these cues, Dacke and her team wondered if dung beetles can use stars for
navigation, just as birds, seals and humans do. After all, they reasoned, dung beetles can
somehow keep straight on clear, moonless nights.
To find out, the researchers timed how long dung beetles of the species Scarabaeus
satyrus took to cross a circular arena with high walls blocking views of treetops and other
landmarks. They tested the insects in South Africa under a moonlit sky, a moonless sky
and an overcast sky. In some trials, the beetles were fitted with cardboard caps, which
kept their eyes to the ground. Overall, the beetles had a difficult time traveling straight
and took significantly longer to cross the arena if caps or clouds obstructed their view of
the sky.
From the experiments, "we thought that they could be using the stars [for orientation], but
dung beetles have such small eyes that they don't have the resolution, or sensitivity, to see
individual stars," Dacke said.
So the researchers moved their setup into a planetarium to tease out the information the
beetles were extracting from the starry sky. They repeated the experiment under several
different conditions, such as showing only the brightest stars, showing only the diffuse
band of the Milky Way and showing the complete starry sky. The beetles took about the
same amount of time to cross the arena when only the Milky Way was visible as when
they could see a full star-filled sky. And they were slower to cross under all other
conditions.
Previous experiments showed another dung beetle, S. zambesianus, is unable to roll along
straight tracks on moonless nights when Earth's galaxy, the Milky Way, lies below the
horizon, Dacke noted. Taken together, these results suggest dung beetles navigate using
the gradient of light provided by the Milky Way. However, this technique would only
work for beetles living in regions where the Milky Wayis distinct. "What they are doing
in the Northern Hemisphere [of Earth], I don't know," she said.
The researchers are now trying to determine the relative importance of the different sky
cues dung beetles use. "If they have the moon, polarized light and the Milky Way, will
they use all cues equally?" Dacke said.
The research is published online today (Jan. 24) in the journal Current Biology.
http://www.livescience.com/26557-dung-beetles-navigate-stars.html
Figure 6.1. Immune Response to Self or Foreign Antigens.
http://stemcells.nih.gov/info/scireport/pages/chapter6.aspx
GI Tract Bacteria May
Protect Against
Autoimmune Disease
Jan. 17, 2013 — Early life exposure to normal bacteria of the GI tract (gut microbes)
protects against autoimmune disease in mice, according to research published on-line in
the January 17 edition of Science. The study may also have uncovered reasons why
females are at greater risk of autoimmune diseases such as multiple sclerosis, rheumatoid
arthritis, and lupus compared to males.
Researchers from The Hospital for Sick Children (SickKids) found that when female
mice at high risk of autoimmune (type 1) diabetes were exposed to normal gut bacteria
from adult male mice, they were strongly protected against the disease. In this type of
mouse strain, more than 85% of females develop autoimmune diabetes due to strong
genetic risk factors. In contrast, only 25% of the females developed the disease after they
were given normal male gut microbes early in life.
"Our findings suggest potential strategies for using normal gut bacteria to block
progression of insulin-dependent diabetes in kids who have high genetic risk," says
principal investigator Dr. Jayne Danska. She is Senior Scientist in Genetics & Genome
Biology at SickKids and Professor in the Departments of Immunology and Medical
Biophysics at the University of Toronto.
A second unexpected finding was the effects of the gut microbe treatments on sex
hormones. "We were surprised to see that when young female mice received normal gut
microbes from adult males, their testosterone levels rose. We then showed that this
hormone was essential for the gut microbe treatment to protect against the disease. It was
completely unexpected to find that the sex of an animal determines aspects of their gut
microbe composition, that these microbes affect sex hormone levels, and that the
hormones in turn regulate an immune-mediated disease," says Dr. Danska.
She adds, "We don't know yet how transfer of male gut microbes into females increases
their testosterone, or how this process protects against autoimmunity. This study opens up
a new research arena to explore the clinical potential of altering the gut microbe
community to prevent or treat immune-mediated diseases."
The hygiene hypothesis
The findings support the 'hygiene hypothesis,' which suggests that the dramatic increase
in autoimmune and inflammatory diseases over the past 50 years results from changes in
our exposure to microbes. Gut microbes are essential for normal development and
training of the immune system, for extracting nutrients from our food, and for protecting
us from some infectious diseases. "Our gut microbial community is an essential part of
ourselves -- bacterial cells outnumber human cells in our bodies by more than ten to one - and we live with them as partners," explains Dr. Danska.
Previous research has shown that children living on farms, exposed to a denser and more
complex microbial environment, have fewer immune-mediated diseases compared to
their village or urban-dwelling peers. This new publication is the first to identify a
difference between normal gut microbes in males and females reared in identical
conditions, and to show that transfer of male-sourced gut bacteria protects against
autoimmune disease in females with high genetic risk.
"Our findings point to a direct relationship between normal gut microbe composition and
prevention of autoimmune disease. From these discoveries we can move on to
characterize the relationships between gut microbes, sex hormones, and ways to control
unwanted immune responses," says Dr. Danska.
Implications for diabetes and other autoimmune diseases
The researchers' success in preventing type 1 diabetes from developing in high-risk mice
suggests that similar approaches may be applicable in preventing and treating other
immune diseases, particularly those showing a female sex bias, Dr. Danska says.
Story Source:
The above story is reprinted from materials provided by Helmholtz Centre For
Environmental Research - UFZ.
Note: Materials may be edited for content and length. For further information, please
contact the source cited above.
Journal Reference:
Janet G. M. Markle, Daniel N. Frank, Steven Mortin-Toth, Charles E. Robertson, Leah
M. Feazel, Ulrike Rolle-Kampczyk, Martin von Bergen, Kathy D. McCoy, Andrew J.
Macpherson, and Jayne S. Danska. Sex Differences in the Gut Microbiome Drive
Hormone-Dependent Regulation of Autoimmunity. Science, January 17, 2013 DOI:
10.1126/science.1233521
http://www.sciencedaily.com/releases/2013/01/130117133003.htm
Designing Life: Should
Babies Be Genetically
Engineered?
By: Wynne Parry, LiveScience Contributor
18 February 2013 - The increasing power and accessibility of genetic technology may one
day give parents the option of modifying their unborn children, in order to spare offspring
from disease or, conceivably, make them tall, well muscled, intelligent or otherwise
blessed with desirable traits.
Would this change mean empowering parents to give their children the best start
possible? Or would it mean designer babies who could face unforeseen genetic problems?
Experts debated on Wednesday evening (Feb. 13) whether prenatal engineering should be
banned in the United States. Humans have already genetically modified animals and
crops, said Sheldon Krimsky, a philosopher at Tufts University, who argued in favor of a
ban on the same for human babies. "But in the hundreds of thousands of trails that failed,
we simply discarded the results of the unwanted crop or animal."
Unknown consequences
Is this a model that society wants to apply to humans, making pinpoint genetic
modifications, only to "discard the results when they don't work out?" Krimsky asked
during an Intelligence Squared Debate held in Manhattan. He added that assuming no
mistakes will occur would be sheer hubris.
He and fellow ban proponent Lord Robert Winston, a professor of science and society
and a fertility expert at Imperial College in London, focused on the uncertainty associated
with the genetic underpinnings of traits. The two also addressed the consequences of
manipulating genes. "Even [for] height, one of the most heritable traits known, scientists
have found at least 50 genes that account for only 2 to 3 percent of the variance in the
samples," Krimsky said. "If you want a tall child, marry tall."
Mother Nature doesn’t care
Meanwhile, their opponents, who opposed the ban, talked of empowering parents to give
their children a healthy life, even if it meant giving their offspring traits they themselves
could not pass down. Lee Silver, a professor of molecular biology and public policy at
Princeton University, urged the audience members to look at someone sitting next to
them.
"That person and you differ at over 1 million locations in your DNA [deoxyribonucleic
acid]. Most [of these variations] don't do anything," Silver said. "[But] even if you are a
healthy adult, 100 [of these] can cause deadly childhood disease in your children or
grandchildren." "Mother Nature is a metaphor," he continued. "And it is a bad metaphor,
because in reality inheritance is a game of craps … It won't have to be that way in the
future."
His fellow ban opponent, Nita Farahany, a professor of law and of genome sciences and
policy at Duke University, attacked the idea that uncertainty should prevent the use of the
technology, pointing out that reproduction, completely unaided by technology, involves
much uncertainty. "We are not going to ban natural sex," Farahany said.
Already possible
A significant portion of the debate focused on a particular technology known as
mitochondrial transfer. While the majority of DNA resides in a cell's nucleus, a small
amount is contained in the cell's energy factories, called mitochondria. This
mitochondrial DNA is passed from mother to child. In rare cases, women have
mitochondrial defects they can pass down to their children, causing devastating problems
or even death.
Mitochondrial transfer can replace such defective mitochondrial DNA with that from a
donor, allowing affected mothers to avoid passing these defects on to their children, who
then carry genetic material from three parents (the father and two mothers, including the
donor).
Opponents of a ban argued it would prevent women with mitochondrial disorders from
having healthy children of their own. "I am not here to defend every type of genetic
engineering. I don't think we are ready as a society to embrace it all," Farahany said.
Rather than an outright ban, she and Silver argued for a middle ground, which would
allow for certain procedures once they had been shown to be safe and effective. An
emerging scientific consensus says mitochondrial transfer would fit into this category,
she said.
Winston disagreed. "We know fiddling with mitochondrial DNA may make a massive
difference to what happens to nuclear DNA. … Abnormal children have been born as
result of mitochondrial transfer," he said. "I think, in preventing one genetic disease, you
are likely to cause another genetic disease."
Society should instead focus on the enormous importance of environmental influences in
health, Winston said. "What we should be trying to do, rather than risk making abnormal
babies, is to improve the environment so the DNA functions in the best possible ways."
Neither Farahany nor Silver argued in favor of allowing parents to modify their children
to ensure other traits that are less medically necessary, but nevertheless desirable, such as
higher intelligence or blue eyes. "What I think parents care about most is promoting the
health of their children," Silver said.
Leading to eugenics?
Both sides referred to the specter of eugenics, an idea embraced by the Nazis, which
holds that selective breeding can be used to improve the human race.
Winston and Krimsky pointed out that genetically modifying children to choose desirable
traits evoked this approach. Meanwhile, Farahany noted that some of the worst abuses of
government in recent history involved attempts to control reproduction. How would a ban
on the genetic modification of children be enforced, she asked, would all babies be
forcibly tested?
An audience votedeclared the opponents of the ban the winners.
http://www.livescience.com/27206-genetic-engineering-babies-debate.html
"Germline" genetic engineering is genetic engineering
that targets the genes in eggs, sperm, or very early
embryos. The alterations affect every cell in the body of
the resulting individual, and are passed on to all future
generations. Germline engineering is banned in many
countries but not in the U.S. Diagram 5 shows how
germline genetic engineering works.
http://www.arhp.org/publications-and-resources/patientresources/printed-materials/cloning
When Water Speaks:
Solvents Make Catalysts
More Efficient
Feb. 21, 2013 — Why certain catalyst materials work more efficiently when they are
surrounded by water instead of a gas phase is unclear. RUB chemists have now gleaned
some initial answers from computer simulations. They showed that water stabilises
specific charge states on the catalyst surface.
"The catalyst and the water sort of speak with each other" says Professor Dominik Marx,
depicting the underlying complex charge transfer processes. His research group from the
Centre for Theoretical Chemistry also calculated how to increase the efficiency of
catalytic systems without water by varying pressure and temperature.
The researchers describe the results in the journals Physical Review Letters and Journal
of Physical Chemistry Letters.
Heterogeneous catalysis: water or gas as the second phase
In heterogeneous catalysis, researchers combine substances with two different phases -usually solid and gas. Chemical reactions work faster at the resulting interfaces than
without a catalyst. Industry uses heterogeneous catalysis for many processes, for example
to transform alcohols into certain aldehydes. Titanium dioxide with gold particles bonded
to the surface, for example, is suitable as the solid phase. Water -- instead of a gas -- as
the second phase has several advantages: environmentally harmful substances which are
required in traditional procedures for the oxidation of alcohols can easily be replaced by
atmospheric oxygen. Also, the whole reaction in water is very efficient, even at moderate
temperatures.
Charge transfer between water and catalyst
The theoretical chemists have studied what happens in the catalysis at the molecular level
by means of so-called ab initio molecular dynamics simulations. The result: a charge
transfer takes place between the water and the catalyst. Electrons, or more specifically
portions of electron densities, are moved between the solid and the liquid phase. The
researchers speculate that in this way the liquid phase stabilises charge states on the gold
surface. The sites where this occurs could be the active centres of the catalyst, where the
chemical reactions work efficiently. Unlike water, a gas phase is not able to "talk" to the
catalyst in this way, because no charge transfer is possible with the gas phase.
Increasing the efficiency through thermodynamics
In a further study, the team led by Dominik Marx examined a related metal/oxide catalyst
of copper and zinc oxide, which is used for the large-scale industrial synthesis of
methanol. As the computer simulations showed, especially the interplay between the
solid phase and the gas phase is important here for the efficiency. Depending on the
pressure and temperature conditions, hydrogen binds to the catalyst surface and thus
indirectly stabilises catalytically active centres that occur in this case due to an electron
transfer between the metal and the oxide. "Without the hydrogen, put bluntly the centres
would not exist," says Marx. In this way, the thermodynamic conditions in the gas phase
put the surface into a certain state which is particularly favorable for the work of the
catalyst.
Added value through combination
The two studies thus show that the catalytic efficiency can be controlled both by a solvent
and by thermodynamics -- namely through the pressure and temperature of the gas phase.
However, completely different mechanisms are responsible for this, which the
researchers were nevertheless able to elucidate using the same simulation methods. This
makes the results directly comparable. In this way, the theorists aim to study in future
whether they can improve the copper/zinc oxide system even further by replacing the gas
phase with a suitable solvent.
Story Source:
The above story is reprinted from materials provided by Ruhr-Universitaet-Bochum.
Note: Materials may be edited for content and length. For further information, please
contact the source cited above.
Journal References:
• Matteo Farnesi Camellone, Dominik Marx. On the Impact of Solvation on a
Au/TiO2Nanocatalyst in Contact with Water. The Journal of Physical
Chemistry Letters, 2013; 4 (3): 514 DOI: 10.1021/jz301891v
• Luis Martínez-Suárez, Johannes Frenzel, Dominik Marx, Bernd Meyer. Tuning the
Reactivity of a Cu/ZnO Nanocatalyst via Gas Phase Pressure. Physical
Review Letters, 2013; 110 (8) DOI: 10.1103/PhysRevLett.110.086108
http://www.sciencedaily.com/releases/2013/02/130221084705.htm
Snapshot of the charge transfer:
Water-induced charge transfer at the
interface between water and catalyst.
The red and blue areas in the left and
right image quantify the decrease or
increase of the electron density due to
the charge transfer at a given time.
The blue and red mesh in the lower
image section represents the oxide,
the grey and yellow balls at the oxide
surface the metal. The small blue and
red molecules in the upper image
section are water molecules. (Credit:
M. Farnesi Camellone, D. Marx)
Photo Gallery:
Translucent
Creatures
http://photography.nationalgeographic.com/photography/photos/translucentcreatures.html#/transparent-cowfish-newbert_18385_600x450.jpg
Juvenile Cowfish
A photographer's strobe gives a
violet sheen to this translucent
juvenile roundbelly cowfish off
the coast of Kona, Hawaii.
Also known as the transparent
boxfish, the roundbelly cowfish
has two short horns in front of
its eyes.
Photograph by Chris Newbert,
Minden Pictures
Pelagic Octopus
A pelagic, or open-ocean, octopus
gives off a neon glow in Hawaii.
Most species of octopus have no
internal skeleton, unlike other
cephalopods.
Photograph by Chris Newbert,
Minden Pictures
Hydromedusa
A hydromedusa spreads
its luminescent
tentacles in the Weddell
Sea near Antarctica.
Photograph by Ingo
Arndt, Minden Pictures
Sea Butterfly Snail
Tiny marine snails known as sea
butterflies take many forms,
including heart-shaped, such as this
species in Antarctica's Weddell Sea.
Photograph by Ingo Arndt, Minden
Pictures
Larval Shrimp
and Jellyfish
A transparent larval
shrimp piggybacks on
an equally seethrough jellyfish in
the waters around
Hawaii.
Photograph by Chris
Newbert, Minden
Pictures
Bristleworm
A close-up of a
bristleworm's head in
Antarctica's Weddell
Sea shows the tiny
predator's trumpetshaped mouth.
Photograph by Ingo
Arndt, Minden
Pictures
Zooplankton
A copepod, a type of zooplankton,
drifts in the Weddell Sea near
Antarctica. Copepods are microscopic
relatives of shrimp and lobsters
Photograph by Ingo Arndt, Minden
Pictures
Comb Jelly
Darkness in Antarctica's Weddell
Sea gives this comb jelly a chance to
show off its candy-colored
bioluminescent cells.
Photograph by Ingo Arndt, Minden
Pictures
Jelly Larva
The flower-shaped
larva of a
scyphomedusa jelly
drifts in Antarctica's
Weddell Sea.
Photograph by Ingo
Arndt, Minden
Pictures
Larval Leaf
Scorpionfish
Lacking any other defense, many
larval fish have adapted
transparency as a method of
camouflage—such as this tiny, seethrough larval leaf scorpionfish in
Hawaii.
Photograph by Chris Newbert,
Minden Pictures
Larval
Flounder
Flounder in their
larval stage, such as
this one in Hawaii,
resemble ghostly
undersize replicas of
adults.
Photograph by Chris
Newbert, Minden
Pictures