Gold Nanoparticles Create Visible-Light Catalysis in Nanowires

A scientist at the U.S. Department of Energy's (DOE) Argonne National Laboratory has created visible-light catalysis, using silver chloride nanowires decorated with gold nanoparticles, that may decompose organic molecules in polluted water.

"Silver nanowires have been extensively studied and used for a variety of applications, including transparent conductive electrodes for solar cells and optoelectronic devices," said nanoscientist Yugang Sun of Argonne's Center for Nanoscale Materials. "By chemically converting them into semiconducting silver chloride nanowires, followed by adding gold nanoparticles, we have created nanowires with a completely new set of properties that are significantly different from the original nanowires."

Traditional silver chloride photocatalytic properties are restricted to ultraviolet and blue light wavelengths, but with the addition of the gold nanoparticles, they become photocatalytic in visible light. The visible light excites the electrons in the gold nanoparticles and initiates reactions that culminate in charge separation on the silver chloride nanowires. Tests have already shown that gold-decorated nanowires can decompose organic molecules such as methylene blue.

"If you were to create a film of gold-decorated nanowires and allow polluted water to flow through it, the organic molecules may be destroyed with visible irradiation from conventional fluorescent light bulbs or the sun," Sun said.

Sun started with traditional silver nanowires that were oxidized with iron chloride to create silver chloride nanowires. A sequential reaction with sodium tetrachloroaurate deposited the gold nanoparticles on the wires.

Sun said it is possible to use a similar mechanism to deposit other metals such as palladium and platinum onto the silver chloride nanowires and create new properties, such as the ability to catalyze the splitting of water into hydrogen with sunlight.

A paper on this research was published in the Journal of Physical Chemistry C.

Funding was provided by the U.S. Department of Energy Office of Science. The Center for Nanoscale Materialsat Argonne National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale, supported by the DOE Office of Science.

Carbon Dioxide Controls Earth's Temperature, New Modeling Study Shows

Water vapor and clouds are the major contributors to Earth's greenhouse effect, but a new atmosphere-ocean climate modeling study shows that the planet's temperature ultimately depends on the atmospheric level of carbon dioxide.

The study, conducted by Andrew Lacis and colleagues at NASA's Goddard Institute for Space Studies (GISS) in New York, examined the nature of Earth's greenhouse effect and clarified the role that greenhouse gases and clouds play in absorbing outgoing infrared radiation. Notably, the team identified non-condensing greenhouse gases -- such as carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons -- as providing the core support for the terrestrial greenhouse effect.

Without non-condensing greenhouse gases, water vapor and clouds would be unable to provide the feedback mechanisms that amplify the greenhouse effect. The study's results are published Oct. 15 inScience.

A companion study led by GISS co-author Gavin Schmidt that has been accepted for publication in the Journal of Geophysical Research shows that carbon dioxide accounts for about 20 percent of the greenhouse effect, water vapor and clouds together account for 75 percent, and minor gases and aerosols make up the remaining five percent. However, it is the 25 percent non-condensing greenhouse gas component, which includes carbon dioxide, that is the key factor in sustaining Earth's greenhouse effect. By this accounting, carbon dioxide is responsible for 80 percent of the radiative forcing that sustains the Earth's greenhouse effect.

The climate forcing experiment described in Science was simple in design and concept -- all of the non-condensing greenhouse gases and aerosols were zeroed out, and the global climate model was run forward in time to see what would happen to the greenhouse effect.

Without the sustaining support by the non-condensing greenhouse gases, Earth's greenhouse effect collapsed as water vapor quickly precipitated from the atmosphere, plunging the model Earth into an icebound state -- a clear demonstration that water vapor, although contributing 50 percent of the total greenhouse warming, acts as a feedback process, and as such, cannot by itself uphold the Earth's greenhouse effect.

"Our climate modeling simulation should be viewed as an experiment in atmospheric physics, illustrating a cause and effect problem which allowed us to gain a better understanding of the working mechanics of Earth's greenhouse effect, and enabled us to demonstrate the direct relationship that exists between rising atmospheric carbon dioxide and rising global temperature," Lacis said.

The study ties in to the geologic record in which carbon dioxide levels have oscillated between approximately 180 parts per million during ice ages, and about 280 parts per million during warmer interglacial periods. To provide perspective to the nearly 1 C (1.8 F) increase in global temperature over the past century, it is estimated that the global mean temperature difference between the extremes of the ice age and interglacial periods is only about 5 C (9 F).

"When carbon dioxide increases, more water vapor returns to the atmosphere. This is what helped to melt the glaciers that once covered New York City," said co-author David Rind, of NASA's Goddard Institute for Space Studies. "Today we are in uncharted territory as carbon dioxide approaches 390 parts per million in what has been referred to as the 'superinterglacial.'"

"The bottom line is that atmospheric carbon dioxide acts as a thermostat in regulating the temperature of Earth," Lacis said. "The Intergovernmental Panel on Climate Change has fully documented the fact that industrial activity is responsible for the rapidly increasing levels of atmospheric carbon dioxide and other greenhouse gases. It is not surprising then that global warming can be linked directly to the observed increase in atmospheric carbon dioxide and to human industrial activity in general."

Cancer is a man-made disease, controversial study claims

Is the common nature of cancer worldwide purely a man-made phenomenon? That is what some researchers now suggest.

Still, other specialists in cancer and in human fossils have strong doubts about this notion.

Cancer is a leading cause of death worldwide, accounting for roughly one in eight of all deaths in 2004, according to the World Health Organization. However, scientists have only found one case of the disease in investigations of hundreds of Egyptian mummies, researcher Rosalie David at the University of Manchester in England said in a statement. (The researchers did not reply to repeated queries made via phone and e-mail.)

The rarity of cancer in mummies suggests it was scarce in antiquity, and "that cancer-causing factors are limited to societies affected by modern industrialization," researcher Michael Zimmerman at Villanova University in Pennsylvania said in a statement. "In an ancient society lacking surgical intervention, evidence of cancer should remain in all cases."

Zimmerman was the first to diagnose cancer in an Egyptian mummy by analyzing its tissues on a microscopic level, identifyingrectal cancer in an unnamed mummy who had lived in the Dakhleh Oasis during the Ptolemaic period 1,600 to 1,800 years ago.

Story: Is it time to return to caveman parenting?

David and Zimmerman also analyzed ancient literature from Egypt and Greece for hints of cancer, as well as medical studies of human and animal remains going back to the age of dinosaurs. They suggested evidence of cancer in animal fossils, non-human primates and early humans was scarce, with a few dozen uncertain examples. As they analyzed ancient literature, they did not find descriptions of operations for breast and other cancers until the 17th century, and the first reports in the scientific literature of distinctive tumors have only occurred in the past 200 years, such as scrotal cancer in chimney sweepers in 1775, nasal cancer in snuff users in 1761 and Hodgkin's disease in 1832.

One possible reason cancers might have been comparatively rare in antiquity is that the short life span of individuals back then precluded the development of the disease. Still, the researchers did note some people in ancient Egypt and Greece did live long enough to develop such diseases as atherosclerosis, Paget's disease of bone, and osteoporosis.

'Sin' of modern societies 

David and Zimmerman therefore argue that cancer nowadays is largely caused by man-made environmental factors such as pollution and diet. They detailed their findings in the October issue of the journal Nature Reviews Cancer.

"In industrialized societies, cancer is second only to cardiovascular disease as a cause of death, but in ancient times, it was extremely rare," David said in a statement. "There is nothing in the natural environment that can cause cancer."

Despite that statement, dinosaurs did develop cancer well before humans were on the scene. Also, others argue the short life spans of antiquity could be a profoundly effective reason as to why cancer might have been rare then.

"Cancer is very rare in modern societies in humans under age 30," oncologist Dr. John Glaspy at UCLA's Jonsson Comprehensive Cancer Center told LiveScience. "In ancient times, people rarely lived to be much older than that. So cancer was rare. The 'sin' of modern societies is having people live to be much older."

Story: 3 ways to lower your breast cancer risk

Another concern when examining the fossil record is that skeletal remains might not preserve cancers very well. "To see cancers with the skeletal record, you really have to have a tumor that's affecting bone," paleoanthropologist John Hawks at the University of Wisconsin at Madison said in a phone interview. "Although there might be few confirmed diagnoses of tumors in bones, it's because cancer is a difficult diagnosis to make from bone."

Hawks did note that modern lifestyles could certainly lead to much higher rates of cancer than in the past, but not necessarily due to pollution.

Not tonight, dear. My head's fine but my back's killing me

Back pain has replaced the headache as the country's biggest passion-killer, according to a survey.

One in ten of us has admitted our sex lives suffer due to back pain  -  with women more likely to give lovemaking a miss because of the problem.

More than half  -  55 per cent  -  of Britons suffer from back pain at least once a month. a quarter of those said they would avoid any strenuous activity when suffering  -  including sex.

One in ten said they had even left the bed to sleep on the floor in an effort to ease the discomfort.

Back pain costs an estimated £7billion every year through work-related absence.

Dr Ralph Rogers, a skeletal specialist at the London Orthopedic clinic, said many patients with back problems wrongly assumed sex would make the condition worse. 'But actually lying still in bed is one of the worst things you can do,' he added.

Physiotherapist Martin Haines said the consumer survey of 8,000 adults carried out by Dynaspine, showed that back pain was having a profound impact.

But he said the problem could be helped by keeping the spine moving and taking gentle exercise.

'The spine is designed to move, not stay still, so using a back support which allows the spine to move is really important,' he added.

Important Misconceptions about sex

Mardon ki tarah aurtein bhi bohut sey jinsi maghaliton (sexual misconceptions) ka shikar hain jo inki azdwajii khushyion mein bohut bari rukawat sabit hote hain. Azdwajii khushyion kay liye khawateen ko na sirf apney bul kay mardon kay jinsi mughaliton ka zikar lya jaey  taa'hum khawateen kay chund ahem jinsi mughlitey kuch yun hain

Air pollution could increase breast cancer risk: study

Traffic-related air pollution may put women at risk for breast cancer, according to a new study from Quebec.

The study, published in the journal Environmental Health Perspectives, looks at links between the risk of breast cancer, a leading cause of death from cancer in women, and traffic pollution.

Researchers from McGill University and the Université de Montréal charted incidences of breast cancer and compared them with pollution maps.

“We’ve been watching breast cancer rates go up for some time,” study co-author Mark Goldberg, a researcher at McGill University Health Centre, said in a release on Wednesday.

“Nobody really knows why, and only about one-third of cases are attributable to known risk factors. Since no one had studied the connection between air pollution and breast cancer using detailed air pollution maps, we decided to investigate it.”

Dr. Goldberg and his colleagues combined data from several studies. They created two air pollution maps which showed levels of nitrogen dioxide, a byproduct of vehicle traffic, in different parts of Montreal in 1996 and 10 years earlier in 1986.

Then, the research team looked at the home addresses of women diagnosed with breast cancer in a 1996-97 study and charted that onto the air pollution maps.

The team says its results were “startling,” and showed the incidence of breast cancer was increased in areas with higher levels of air pollution.

“We found a link between post-menopausal breast cancer and exposure to nitrogen dioxide (NOsub2/sub), which is a marker for traffic-related air pollution,” Dr. Goldberg said in the release.

“Across Montreal, levels of NOsub2/sub varied between five parts per billion to over 30 parts per billion. We found that risk increased by about 25% with every increase of NOsub2/sub of five parts per billion.

“Another way of saying this is that women living in the areas with the highest levels of pollution were almost twice as likely to develop breast cancer as those living in the least polluted areas.”

Dr. Goldberg warns, however, that the study must be interpreted with caution.

“First of all, this doesn’t mean NOsub2/sub causes breast cancer,” he said. “This gas is not the only pollutant created by cars and trucks, but where it is present, so are the other gases, particles and compounds we associate with traffic — some of which are known carcinogens.”

Dr. Goldberg said the study can be subject to unknown variables and that some areas of uncertainty remain.

“For example, we don’t know how much the women in the study were exposed to pollution while at home or at work, because that would depend on their daily patterns of activity, how much time they spend outdoors and so on,” Dr. Goldberg said.

“At the moment, we are not in a position to say with assurance that air pollution causes breast cancer. However, we can say that the possible link merits serious investigation,” the team said in its release.

Studies published in the U.S, have also shown possible links between cancer and air pollution.

The study was funded by a research grant from the Canadian Cancer Society and another one from the Canadian Institutes of Health Research.

Doctors give teenager artificial heart

Doctors in Italy have implanted an artificial heart into a 15-year-old boy, the first time the procedure has been performed on a child.

Heart surgeons at Rome's Bambino Gesu Children's Hospital carried out the 10-hour breakthrough operation on Thursday, and the hospital said it was "cautious" over the boy's condition.

"A permanent artificial heart in the inside of the chest was implanted for the first time on an (adolescent) patient. So far this type of implant has only taken place on adults," the hospital in a statement on Saturday.

Artificial hearts are usually used on a temporary basis for patients awaiting a suitable human transplant, but the boy suffered from an illness that made a long wait impossible.

The artificial heart is four centimetres wide and weighs 400 grams, and special measures were taken to reduce the risk of infection.

"The risk of infection represents the primary cause of failure of alternative solutions attempted to date worldwide," said the hospital.

The procedure "opened new therapeutic perspectives and hope for life for all patients with cardiac illnesses for whom a transplant is needed, especially for those like Thursday's patient who cannot receive a donated heart for clinical reasons," the statement said.