Chemists at Indiana University
Bloomington have designed a molecule that binds chloride
ions - but can be conveniently compelled to release the ions
in the presence of ultraviolet light.
X-ray fluorescence spectroscopy unveils
Da Vinci?s astounding sfumato technique.
Image:
Non-invasive X-ray fluorescence
spectroscopy was used to reveal the sfumato paint layer
stacking method that was used by Leonardo da Vinci to
paint the faces in seven of his paintings.
Study of electron orbits in multilayer graphene finds unexpected energy gaps.
This graphic shows electrons that move along an equipotential, while those that follow closed equipotentials (as in a potential-energy valley) become localized (right).
For the first time ever, physicists from the Laboratory for Attosecond Physics (LAP) at the Max Planck Institute of Quantum Optics have observed what occurs inside an atom from which a single electron has been ejected. They report their findings in Nature.
[Image credit: Dr. Christian Hackenberger,
Ludwig-Maximillians University, Munich, Germany].
Individual molecules and their dynamics can also be made visible in living cells using conventional fluorophores at a resolution of around 20 nanometers. How this is done is being revealed for the first time by researchers in the journal ?Nature Methods?.
Help from the dark side: Using dark channel fluorescence, scientists can explain how biochemical substances carry out their function.
Image:
X-ray photon taking electron from the Fe(III) active center to the water mixed orbital in time scale faster than 7 femtoseconds (the core-hole life time of Fe(III).
[Credit: Helmholtz-Zentrum Berlin f? Materialien und Energie, HZB]
Empa grows 'sea urchin'-shaped structures. More efficient photocells thanks to nanostructured surfaces.
Image: These are "sea urchins" made of tiny polystyrene balls, with zinc oxide nanowire "spines" are created using a simple electrochemical process.
[Credit: EMPA]
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More News (open access):
Best way to pour champagne? 'Down the side' wins
first scientific test
In a study that may settle a long-standing
disagreement over the best way to pour a glass of champagne,
scientists in France are reporting that pouring bubbly in an angled,
down-the-side way is best for preserving its taste and fizz. The study
also reports the first scientific evidence confirming the importance
of chilling champagne before serving to enhance its taste, the
scientists say. Their report appears in ACS' bi-weekly Journal of
Agricultural and Food Chemistry.
G?ard Liger-Belair and colleagues note that tiny
bubbles are the essence of fine champagnes and sparkling wines. Past
studies indicate that the bubbles - formed during the release of large
amounts of dissolved carbon dioxide gas - help transfer the taste,
aroma, and mouth-feel of champagne. Scientists long have suspected
that the act of pouring a glass of bubbly could have a big impact on
gas levels in champagne and its quality. Until now, however, no
scientific study had been done.
The scientists studied carbon dioxide loss in
champagne using two different pouring methods. One involved pouring
champagne straight down the middle of a glass. The other involved
pouring champagne down the side of an angled glass. They found that
pouring champagne down the side preserved up to twice as much carbon
dioxide in champagne than pouring down the middle ? probably because
the angled method was gentler. They also showed that cooler champagne
temperatures (ideally, 39 degrees Fahrenheit) help reduce carbon
dioxide loss.
Toward safer plastics that lock in potentially
harmful plasticizers
Scientists have published the first report on a new
way of preventing potentially harmful plasticizers from migrating from
one of the most widely used groups of plastics. The advance could lead
to a new generation of polyvinyl chloride (PVC) plastics that are
safer than those now used in packaging, medical tubing, toys, and
other products, they say. Their study is in ACS' Macromolecules, a
bi-weekly journal.
Helmut Reinecke and colleagues note that
manufacturers add large amounts of plasticizers to PVC to make it
flexible and durable. Plasticizers may account for more than one-third
of the weight of some PVC products. Phthalates are the mainstay
plasticizers. Unfortunately, they migrate to the surface of the
plastic over time and escape into the environment. As a result, PVC
plastics become less flexible and durable. In addition, people who
come into contact with the plastics face possible health risks. The U.
S. Consumer Product Safety Commission in 2009 banned use of several
phthalate plasticizers for use in manufacture of toys and child care
articles.
The scientists describe development of a way to
make phthalate permanently bond, or chemically attach to, the internal
structure of PVC so that it will not migrate. Laboratory tests showed
that the method completely suppressed the migration of plasticizer to
the surface of the plastic. "This approach may open new ways to the
preparation of flexible PVC with permanent plasticizer effect and zero
migration," the article notes.
Oil-eating bacteria may determine environmental
impact of Gulf oil
The environmental impact of millions of gallons of
oil still in the Gulf of Mexico from the Deepwater Horizon incident
may depend on microscopic helpers: Bacteria that consume oil and other
hydrocarbons and could break down the spilled crude, making it
disappear. That's the topic of an article in the current issue of
Chemical & Engineering News (C&EN), ACS' weekly newsmagazine.
It points out that the oil-eating bacteria are
beneficial in helping to clear away the oil. Their activity, however,
could eventually pose risks to the Gulf's ecosystem, particularly in
the deep ocean. The oil acts as a huge source of food and could
produce bacteria "blooms," or massive population explosions. As the
blooms die and decay, they remove oxygen from the Gulf water,
jeopardizing the health of fish and other aquatic animals.
The article discusses scientific research underway
to shed light on the bacteria's effects. It notes that the oxygen
depletion so far is not as serious as the Gulf of Mexico's infamous
"dead zone," an 8,000 square mile area - about the size of New Jersey
- with oxygen levels too low for fish to survive. The Gulf's oil
plumes cause nearly a 35 percent oxygen drop compared to a 90 percent
drop in that dead zone.
Chemical & Engineering News: "Microbes
to the Rescue" [Volume 88, Number 32pp. 32 - 33; DOI:
10.1021/CEN080210163345].
Deathstalker scorpion venom could improve gene
therapy for brain cancer
An ingredient in the venom of the "deathstalker"
scorpion could help gene therapy become an effective treatment for
brain cancer, scientists are reporting. The substance allows
therapeutic genes - genes that treat disease - to reach more brain
cancer cells than current approaches, according to the study in ACS
Nano, a monthly journal.
Miqin Zhang and colleagues note that gene therapy -
the delivery of therapeutic genes into diseased cells - shows promise
for fighting glioma, the most common and most serious form of brain
cancer. But difficulties in getting genes to enter cancer cells and
concerns over the safety and potential side effects of substances used
to transport these genes have kept the approach from helping patients.
The scientists describe a new approach that could
solve these problems. Key ingredients of their gene-delivery system
are chlorotoxin, the substance in deathstalker scorpion venom that can
slow the spread of brain cancer, and nanoparticles of iron oxide. Each
nanoparticle is about 1/50,000th the width of a human hair. In tests
on lab mice, the scientists demonstrated that their venom-based
nanoparticles can induce nearly twice the amount of gene expression in
brain cancer cells as nanoparticles that do not contain the venom
ingredient. "These results indicate that this targeted gene delivery
system may potentially improve treatment outcome of gene therapy for
glioma and other deadly cancers," the article notes.
This skin tumor is shown after
treatment with a new contrast agent that can improve the
visualization of skin cancer cells using an advanced medical
imaging device.
Credit: American Chemical Society
Scientists are reporting development of a substance
to enhance the visibility of skin cancer cells during scans with an
advanced medical imaging system that combines ultrasound and light.
The hybrid scanner could enable doctors to detect melanoma, the most
serious form of skin cancer, in its earliest and most curable stages,
the report in the monthly journal ACS Nano indicates.
Lihong Wang, Younan Xia, and colleagues point out
that early diagnosis is key to improving survival in patients with
melanoma. The five-year survival rate for melanoma is about 98 percent
if detected early but can be as low as 15 percent when detected at an
advanced stage. Existing imaging techniques for early detection of
melanoma produce low-quality images, can "see" only a fraction of an
inch below the skin, and use potentially harmful radioactive
materials. A promising new technique called photoacoustic tomography
(PAT) can overcome these problems. The system shoots light into
tumors, which slightly heats up the cancer cells and produces high
frequency sound waves that provide images of the tumor. But the PAT
system lacks an optimal contrast agent that can easily enter skin
cancer cells and make them visible.
The scientists developed such an agent by attaching
a peptide (one of the building blocks of proteins) that targets skin
cancer cells to gold "nanocages." These hollow gold nanoparticles have
a box-like shape and are barely 1/50,000th the width of a human hair.
When injected into mice with skin cancer, the nanocages improved the
image quality of the cancer cells by three-fold compared to
nanoparticles lacking the peptide. The gold nanocages also show
promise as a way to kill skin cancer cells using heat or anti-cancer
drugs, they add.
Fast forensic test can match suspects' DNA with
crime samples in 4 hours
Crime-solving may get a boost
using a new test that can match suspects' DNA with that of samples
from crime scenes in just four hours.
[Credit: iStock]
A newly developed test could make checking DNA from
people arrested for crimes with DNA samples from crime scenes stored
in forensic databases almost as easy as matching fingerprints. With
the test, police could check on whether a person's DNA matches that
found at past crime scenes while suspects are still being processed
and before a decision on whether to release them on bail. A report on
the fast forensic test appeared in the ACS' Analytical Chemistry, a
semi-monthly journal.
Andrew Hopwood, Frederic Zenhausern, and colleagues
explain that some criminals are arrested, spend less than a day in
jail, and then commit crimes while they are out on bail. If police
could quickly test the suspects' DNA, to see if their genetic material
matches entries in crime databases, they may be able to keep the most
dangerous people locked up. But currently, most genetic tests take
24-72 hours, and by the time that the results are back, the suspects
often have been released.
To increase the speed of forensic DNA testing, the
scientists built a chip that can copy and analyze DNA samples taken
from a cotton swab. Forensic technicians can collect DNA from suspects
by swabbing their mouth, mixing the sample with a few chemicals, and
warming it up. The DNA-testing-lab-on-a-chip does the rest. The entire
process takes only four hours at present. Hopwood and Zenhausern teams
are already optimizing it and reducing the cycle time down to two
hours. Once that is done, police could even double-check their DNA
evidence before releasing a suspect.
Traveling by car increases global temperatures
more than by plane, but only in long term
Traveling by car contributes to
global warming much more than traveling by bus, motorcycle, or
train.
[Credit: iStock]
Driving a car increases global temperatures in the
long run more than making the same long-distance journey by air
according to a new study. However, in the short run travelling by air
has a larger adverse climate impact because airplanes strongly affect
short-lived warming processes at high altitudes. The study appeared in
ACS' Environmental Science & Technology, a semi-weekly journal.
In the study, Jens Borken-Kleefeld and colleagues
compare the impacts on global warming of different means of transport.
The researchers use, for the first time, a suite of climate chemistry
models to consider the climate effects of all long- and short-lived
gases, aerosols and cloud effects, not just carbon dioxide, resulting
from transport worldwide. They concluded that in the long run the
global temperature increase from a car trip will be on average higher
than from a plane journey of the same distance. However, in the first
years after the journey, air travel increases global temperatures four
times more than car travel. Passenger trains and buses cause four to
five times less impact than automobile travel for every mile a
passenger travels. The findings prove robust despite the scientific
uncertainties in understanding the earth's climate system.
"As planes fly at high altitudes, their impact on
ozone and clouds is disproportionately high, though short lived.
Although the exact magnitude is uncertain, the net effect is a strong,
short-term, temperature increase," explains Dr. Jens Borken-Kleefeld,
lead author of the study. "Car travel emits more carbon dioxide than
air travel per passenger mile. As carbon dioxide remains in the
atmosphere longer than the other gases, cars have a more harmful
impact on climate change in the long term."
Homes of the poor and the affluent both have high
levels of endocrine disruptors
Homes in low-income and affluent communities in
California both had similarly high levels of endocrine disruptors, and
the levels were higher in indoor air than outdoor air, according to a
new study believed to be the first that paired indoor and outdoor air
samples for such wide range (104) of these substances. The study
appeared in ACS' Environmental Science & Technology, a semi-monthly
journal.
Ruthann Rudel and colleagues note concern about the
reproductive and other health effects of endocrine disrupting
compounds (EDCs), which are found in many products used in the home.
Examples include phthalates, which are found in vinyl and other
plastics, and polychlorinated biphenyls (PCBs), which are found in
older paints, electrical equipment, and building materials. EDCs also
are among the ingredients in some pesticides, fragrances, and other
materials.
The scientists analyzed indoor and outdoor air
samples as well as house dust in homes from two different communities
in the San Francisco Bay area for the presence of 104 compounds,
including 70 suspected EDCs. The sampling, which took place in 2006,
included 40 homes in Richmond, Calif., an urban, industrial,
low-income area, and 10 homes in Bolinas, Calif., an affluent, coastal
community. Levels were generally higher indoors than outdoors - 32 of
the compounds occurred in higher concentrations indoors and only 2
were higher outdoors. The scientists expressed surprise at finding
higher concentrations of some phthalates outdoors near urban homes
contributing to higher indoor levels as well, but concluded that EDCs
"are ubiquitously common across socioeconomic groups."
Solving the mystery of bone loss from drug for
epilepsy and bipolar disorder
A doctor examines an x-ray of a
hip joint for signs of bone loss, which can occur following
long-term use of a medicine widely used to treat epilepsy,
anxiety, and other conditions.
[Credit: iStock]
Scientists are reporting a possible explanation for
the bone loss that may occur following long-term use of a medicine
widely used to treat epilepsy, bipolar disorder, and other conditions.
The drug, valproate, appears to reduce the formation of two key
proteins important for bone strength, they said. Their study, which
offers a solution to a long-standing mystery, appeared in ACS' monthly
Journal of Proteome Research.
Glenn Morris and colleagues point out that use of
valproate, first introduced more than 40 years ago for the prevention
of seizures in patients with epilepsy, has expanded. Valproate now is
prescribed for mood disorders, migraine headache, and spinal muscular
atrophy (SMA), a rare genetic disease that causes loss of muscle
control and movement. Many SMA patients develop weak bones as a result
of the disease itself, making further bone loss from valproate
especially undesirable. Doctors have known about the bone-loss side
effect, but until now, there has been no molecular explanation.
In an effort to determine why bone loss occurs, the
scientists profiled valproate's effects on more than 1,000 proteins in
the cells of patients with SMA. They found that valproate reduced
production of collagen, the key protein that gives bone its strength,
by almost 60 percent. The drug also reduced levels of osteonectin,
which binds calcium and helps maintain bone mass, by 28 percent. "The
results suggest a possible molecular mechanism for bone loss following
long-term exposure to valproate," the article notes.
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