USA - Scientists create highly transparent solar cells for windows that generate electricity

UCLA researchers have developed a new transparent solar cell that is an advance toward giving windows in homes and other buildings the ability to generate electricity while still allowing people to see outside. Their study appears in the journal ACS Nano.

The UCLA team describes a new kind of polymer solar cell (PSC) that produces energy by absorbing mainly infrared light, not visible light, making the cells nearly 70% transparent to the human eye. They made the device from a photoactive plastic that converts infrared light into an electrical current.

"These results open the potential for visibly transparent polymer solar cells as add-on components of portable electronics, smart windows and building-integrated photovoltaics and in other applications," said study leader Yang Yang, a UCLA professor of materials science and engineering, who also is director of the Nano Renewable Energy Center at California NanoSystems Institute (CNSI).

Yang added that there has been intense world-wide interest in so-called polymer solar cells. "Our new PSCs are made from plastic-like materials and are lightweight and flexible," he said. "More importantly, they can be produced in high volume at low cost."

Polymer solar cells have attracted great attention due to their advantages over competing solar cell technologies. Scientists have also been intensely investigating PSCs for their potential in making unique advances for broader applications. Several such applications would be enabled by high-performance visibly transparent photovoltaic (PV) devices, including building-integrated photovoltaics and integrated PV chargers for portable electronics.

Previously, many attempts have been made toward demonstrating visibly transparent or semitransparent PSCs. However, these demonstrations often result in low visible light transparency and/or low device efficiency because suitable polymeric PV materials and efficient transparent conductors were not well deployed in device design and fabrication.

A team of UCLA researchers from the California NanoSystems Institute, the UCLA Henry Samueli School of Engineering and Applied Science and UCLA's Department of Chemistry and Biochemistry have demonstrated high-performance, solution-processed, visibly transparent polymer solar cells through the incorporation of near-infrared light-sensitive polymer and using silver nanowire composite films as the top transparent electrode. The near-infrared photoactive polymer absorbs more near-infrared light but is less sensitive to visible light, balancing solar cell performance and transparency in the visible wavelength region.

Another breakthrough is the transparent conductor made of a mixture of silver nanowire and titanium dioxide nanoparticles, which was able to replace the opaque metal electrode used in the past. This composite electrode also allows the solar cells to be fabricated economically by solution processing. With this combination, 4% power-conversion efficiency for solution-processed and visibly transparent polymer solar cells has been achieved.

"We are excited by this new invention on transparent solar cells, which applied our recent advances in transparent conducting windows (also published in ACS Nano) to fabricate these devices," said Paul S.Weiss, CNSI director and Fred Kavli Chair in NanoSystems Sciences.

More information: pubs.acs.org/doi/pdf/10.1021/nn3029327

Journal reference: ACS Nano

Provided by University of California, Los Angeles

http://phys.org/news/

Japan - Japan Restarts Oi Nuclear Plant Amidst Protests

On Sunday evening amidst huge public protests, engineers at the Kansai Electric Company pulled out the control rods in the Oi reactor core number three allowing nuclear fusion to resume.

AsianScientist (Jul. 3, 2012) – On Sunday evening amidst huge public protests, engineers at the Kansai Electric Company pulled out the control rods in the Oi reactor core number three allowing nuclear fusion to resume.

It was a historic moment since it marked the restart of a nuclear plant which had been shut down along with 49 other units post-Fukushima.

The operator hoped to have a sustained nuclear reaction by Monday morning and the first transmission of electricity on Wednesday. Japan depends upon nuclear energy for about one-third of its electric supply.

The decision to restart the reactor was taken during a cabinet meeting by Japanese Prime Minister Yoshihiko Noda on June 17, 2012. The PM explained that it was necessary to restart the reactor to !void power shortages in the heavily urbanized Kansai region.

But at the same time Noda also said that Japan must think of ways to do away on its dependence on nuclear energy in a phased manner.

The restarting was marked by a series of public protests, and over the weekend more than 200 protestors blocked the road to the plant. Kansai Electric said that it had enough employees to restart the reactor.

But a report in the Monday’s edition of The New York Times stated that a senior vice president from the ministry in charge of nuclear power had to be ferried to the plant by boat.

In Tokyo about 1,0p0 protestors marched on Sunday in the central part of the city, two days after tens of thousands of people chanted anti-nuclear slogans outside the PM’s residence.

Meanwhile in India officials of the Nuclear Power Corporation have indicated that the first unit of the controversial Kudankulam atomic power station in Tamil Nadu could become operational by August 2012 and the second unit by March 2013.

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Copyright: Asian Scientist Magazine.

Srinivas Laxman | Top News

http://www.asianscientist.com/

USA - Soy doesn't boost brainpower in older women

NEW YORK - Taking daily soy supplements doesn't improve thinking and memory skills or keep them from declining in older women, new findings suggest.

The study of 313 postmenopausal women showed those who took 25 extra grams of soy protein each day improved slightly more than other women on a test of visual memory, or remembering faces. But there was no difference in their overall cognitive skills, compared to women who were given regular milk protein.

Studies have typically come to conflicting or disappointing findings on the role of soy in easing hot flashes and other symptoms of menopause, as well as treating high cholesterol and build-up in the arteries.

And there's been some worry that soy may be risky for breast cancer survivors, though new research has partially eased those concerns.

Regardless of any other effects, the nutritional benefits of soy - including high protein and fiber and low fat --may make it a good diet addition for some people, researchers said.

"There might be a lot of reasons why healthy middle-aged older women might want to take soy supplements, but cognitive function shouldn't be the driving reason for that," Dr. Victor Henderson, the study's lead author from Stanford University, told Reuters Health.

Researchers have thought certain natural plant-derived chemicals in soy might affect changes that happen during menopause, including disturbances in memory, because of their similarity to estrogen produced by the body.

For the new study, Henderson and his colleagues gave women age 45 to 92 a battery of thinking and memory tests, then randomly assigned them to take 25 grams of soy or milk protein supplements, offered in bar and powder form, each day for two and a half years.

Over the study period, women in both groups tended to improve in their overall thinking and memory skills - probably because they'd all taken the tests once before.

However, there was no difference in their improvement on the combination of cognitive tests - or on any individual exam other than visual memory - based on what type of protein supplement the women were taking, the researchers reported Monday in the journal Neurology.

That was also the case when Henderson's team looked specifically at women younger than 60, who had more recently gone through menopause and may have had more to gain from the extra soy.

It's possible soy might still be beneficial for cognition and health in general, but that starting the supplements after menopause is too late to reap any benefits, according to William Wong, who has studied soy in older women at Baylor College of Medicine in Houston, Texas.

"We are all looking for a magic bullet," he told Reuters Health. "But we don't ever think about, well, women in Asian countries have been taking that product (soy) since birth, essentially. There could be some long-term effect that we don't see in the US"

Wong, who wasn't involved in the new study, said one limitation of the research is the relatively small group of women involved and the large variation in age and time since menopause - which might make it harder to determine a specific group of women that could benefit from soy.

Still, he said his own findings on the effect of soy supplements on bone health and blood pressure have been "discouraging."

One recent study of women with a history of breast cancer, however, did suggest those who ate a lot of soy were 25 per cent less likely to have their cancer come back - despite some concern about the estrogen-like effects of soy in breast cancer survivors.

Henderson's team concluded that postmenopausal women should not take soy with the goal of improving their cognitive skills, but that they can eat a diet high in soy if they choose, without worrying that it may have any negative effects on memory.

Reuters