Chinese team develop fuel cell that can clean water as it generates electricity

Yanbiao Liu and his colleagues from Shanghai Jiao Tong University, have succeeded in building a device capable of both cleaning wastewater and producing electricity from it. Using light as an energy source the team created a photo-catalytic fuel cell that used a titanium dioxide nanotube-array anode and a cathode based on platinum. The light energy degrades the organic material found in the wastewater and in the process generates electrons which pass through the cathode converting it into electricity. The team has published its results on Water Science & Technology.

Liu notes in the paper, that wastewater (the stuff that goes down the toilet when flushed) or sewage, as it’s more commonly known in other countries, is a great source of environmental pollution and at the same time, is a truly important and often overlooked source of energy, which, unfortunately generally is not collected and used. It’s also an expensive by-product of human existence. Every day billions of people contribute to the ever growing problem of what to do with all the human waste that is created.

In addition to organic material, wastewater often contains other materials that need to be removed in order to reuse the water for other purposes. In their lab the team tested their fuel cell’s ability to separate clear aromatics (perfumes), azo dyes, pharmaceuticals, personal care products and endocrine-disrupting compounds (birth control pill chemicals that wind up in urine) from wastewater samples and found they were able to separate them completely from the organic material thus producing clean water.

To allow the system to use visible and regular sunlight rather than UV, the team modified the electrodes with semiconductors (such as CdS) which means of course the system, if industrialized, could be used outside as an add-on perhaps to existing wastewater treatment plants.
So far the team hasn’t listed cost estimates for building an electrical/wastewater treatment facility with their new technology, but it’s not hard to see how useful such a plant would be in areas where sewage is sometimes not treated at all, but simply dumped into rivers or streams, or worse, in the streets. In addition to helping clean up such places, the people in those areas would benefit from the electricity that would be produced in the process.

More information: A TiO2-nanotube-array-based photocatalytic fuel cell using refractory organic compounds as substrates for electricity generation, Chem. Commun., 2011, Advance Article, DOI: 10.1039/C1CC13388H

Abstract
A TiO2-nanotube-array-based photocatalytic fuel cell system was established for generation of electricity from various refractory organic compounds and simultaneous wastewater treatment. The present system can respond to visible light and produce obviously enhanced cell performance when a narrow band-gap semiconductor (i.e. Cu2O and CdS) was combined with TiO2 nanotubes.

 

Safer, more effective skin-whitening creams from ancient Chinese herbal medicine

Scientists today reported discovery of the active ingredients in an herb used in traditional Chinese medicine for skin whitening, changing skin color to a lighter shade. The ingredients are poised for clinical trials as a safer, more effective alternative to skin whitening creams and lotions that millions of women and some men use in Asia and elsewhere, they said. The report was among more than 9,500 presentations this week at the 241st National Meeting & Exposition of the American Chemical Society (ACS).

The finding, which caps an intense search for these natural skin lightening substances, could be a boon to women in Asian countries, said study leader Hui-Min Wang, Ph.D. He explained that skin whitening products are all the rage there, but too-often accompanied by itching, redness, inflammation, and other side effects.

"Toxic skin whitening creams are a growing threat to women's health, especially in Asia," Wang said. "We hope that our product will improve lives and provide a safer, more natural way to lighten skin. A cream based on these herbal ingredients could be available on store shelves in as little as a year."

Skin-whitening is big business in countries like China, Japan, Korea, and India, where many women view whiter skin as a symbol of beauty, good health, and high social status. One study estimates that half the women in Asian countries use skin lightening creams, spending the equivalent of several billion dollars annually. People also use such products to fade unsightly age spots, freckles, and scars that have collected pigment.

Dozens of skin whitening creams, lotions, and other products are on sale throughout Asia. Some products contain toxic mercury, hydroquinone, and other potentially toxic substances that can cause redness, itching, inflammation and other skin problems. Some whitening ingredients could increase the risk of skin cancer when used frequently and at high doses, Wang said, citing the need for safer, more effective alternatives.

Wang and colleagues say that they have found a promising alternative in the form of an herbal "cure-all" used in traditional Chinese medicine in the form of soup or tea. The evergreen bush, Cinnamomum subavenium, is a close relative of the trees whose inner bark is the source of cinnamon. The scientists isolated two chemicals from the plant that have the ability to block tyrosinase, an enzyme that controls the synthesis of melanin, a dark pigment responsible for coloring skin, hair, and eyes. Inhibiting tyrosinase is one of the major strategies for skin-whitening, Wang said.

They tested these so-called "melanogenesis inhibitors" on the embryos of zebrafish, which are widely used as stand-ins for people and other animals in biomedical research. The embryos contain a highly visible band of black pigment. Exposure to low levels of the two chemicals reduced melanin production in the fish embryos by almost 50 percent within just four days, turning the embryos snowy white, the scientists said.

"When we saw the results, we were amazed," said Wang, who is with Kaohsiung Medical University in Taiwan. "My first thought was, well, 'If these herbal whiteners can transform zebrafish embryos from black to white, maybe they can also lighten women's skin.'"

He estimated that the chemicals are 100 times more effective in reducing melanin pigmentation than the common skin whitening agents kojic acid and arbutin, which have been used in cosmetics for more than 30 years. The substances did not appear to be toxic when tested in low doses on both cultured human skin cells and zebrafish embryos, Wang noted.

Wang is looking forward to clinical trials of a new beauty product based on the ingredients. Just a one percent solution of the chemicals could achieve dramatic skin whitening, Wang said, adding that several cosmetic companies are working with his group. Wang and his colleagues have applied for patents in the U.S., Japan, and Taiwan.

Provided by American Chemical Society (news : web)

Solving a traditional Chinese medicine mystery

Researchers at the Johns Hopkins School of Medicine have discovered that a natural product isolated from a traditional Chinese medicinal plant commonly known as thunder god vine, or lei gong teng, and used for hundreds of years to treat many conditions including rheumatoid arthritis works by blocking gene control machinery in the cell. The report, published as a cover story of the March issue of Nature Chemical Biology, suggests that the natural product could be a starting point for developing new anticancer drugs.

"Extracts of this medicinal plant have been used to treat a whole host of conditions and have been highly lauded for anti-inflammatory, immunosuppressive, contraceptive and antitumor activities," says Jun O. Liu, Ph.D., a professor of pharmacology and molecular sciences at Johns Hopkins. "We've known about the active compound, triptolide, and that it stops cell growth, since 1972, but only now have we figured out what it does."

Triptolide, the active ingredient purified from the plant Tripterygium wilfordii Hook F, has been shown in animal models to be effective against cancer, arthritis and skin graft rejection. In fact, says Liu, triptolide has been shown to block the growth of all 60 U.S. National Cancer Institute cell lines at very low doses, and even causes some of those cell lines to die. Other experiments have suggested that triptolide interferes with proteins known to activate genes, which gives Liu and colleagues an entry point into their research.

The team systematically tested triptolide's effect on different proteins involved with gene control by looking at how much new DNA, RNA and protein is made in cells. They treated HeLa cells with triptolide for one hour, compared treated to untreated cells and found that triptolide took much longer to have an effect on the levels of newly made proteins and DNA, yet almost immediately blocked manufacture of new RNA. The researchers then looked more closely at the three groups of enzymes that make RNA and found that low doses of triptolide blocked only one, RNAPII.

But the RNAPII enzyme complex actually requires the assistance of several smaller clusters of proteins, according to Liu, which required more investigative narrowing down. Using a small gene fragment in a test tube, the researchers mixed in RNAPII components and in some tubes included triptolide and some not to see which combinations resulted in manufacture of new RNA. Every combination of proteins that included a cluster called TFIIH stopped working in the presence of triptolide.

But again, TFIIH is made of 10 individual proteins, many of which, according to Liu, have distinct and testable activities. Using information already known about these proteins and testing the rest to see if triptolide would alter their behaviors, the research team finally found that triptolide directly binds to and blocks the enzymatic activity of one of the 10, the XPB protein.

"We were fairly certain it was XPB because other researchers had found triptolide to bind to an unknown protein of the same size, but they weren't able to identify it," says Liu. "

To convince themselves that the interaction between triplotide and XPB is what stops cells from growing, the researchers made 12 chemicals related to triplotide with a wide range of activity and treated HeLa cells with each of the 12 chemicals at several different doses. By both counting cells and testing XPB activity levels, the team found that the two correlate; chemicals that were better at decreasing XPB activity were also better at stopping cell growth and vice versa.

"Triptolide's general ability to stop RNAPII activity explains its anti-inflammatory and anticancer effects," says Liu. "And its behavior has important additional implications for circumventing the resistance that some cancer cells develop to certain anticancer drugs. We're eager to study it further to see what it can do for future cancer therapy."

Provided by Johns Hopkins Medical Institutions

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