Carbon foam: The key ingredient of a better battery?

Researchers at Michigan Technological University are working on it. Actually, their design is a twist on what’s called an asymmetric capacitor, a new type of electrical storage device that’s half capacitor, half battery. It may be a marriage made in heaven.

Capacitors store an electrical charge physically and have important advantages: they are lightweight and can be recharged (and discharged) rapidly and almost indefinitely. Plus, they generate very little heat, an important issue for electronic devices. However, they can only make use of about half of their stored charge.

Batteries, on the other hand, store electrical energy chemically and can release it over longer periods at a steady voltage. And they can usually store more energy than a capacitor. But batteries are heavy and take time to charge up, and even the best can’t be recharged forever.

Enter asymmetric capacitors, which bring together the best of both worlds. On the capacitor side, energy is stored by electrolyte ions that are physically attracted to the charged surface of a carbon anode. Combined with a battery-style cathode, this design delivers nearly double the energy of a standard capacitor.

Now, Michigan Tech researchers have incorporated a novel material on the battery side to make an even better asymmetric capacitor.

Their cathode relies on nickel oxyhydroxide, the same material used in rechargeable nickel-cadmium or nickel-metal hydride batteries. “In most batteries that contain nickel oxyhydroxide, metallic nickel serves as a mechanical support and a current collector,” said chemistry professor Bahne Cornilsen, who had been studying nickel electrodes for a number of years, initially with NASA support. A few years ago, the Michigan Tech team had a chance to experiment with something different: carbon foam.  He suggested replacing the nickel with carbon foam. 

Carbon foam has advantages over nickel. “It’s lighter and cheaper, so we thought maybe we could use it as a scaffold, filling its holes with nickel oxyhydroxide,” said Tony Rogers, associate professor of chemical engineering.

Carbon foam has a lot of holes to fill. “The carbon foam we are using has 72 percent porosity,” Rogers said. “That means 72 percent of its volume is empty space, so there's plenty of room for the nickel oxyhydroxide. The carbon foam could also be made of renewable biomass, and that’s attractive.”

But how many times can you recharge their novel asymmetric capacitor? Nobody knows; so far, they haven’t been able to wear it out. “We’ve achieved over 127,000 cycles,” Rogers said.

Other asymmetric capacitors have similar numbers, but none have the carbon-foam edge that could make them even more desirable to consumers.

“Being lighter would give it a real advantage in handheld power tools and consumer electronics,” said Rogers. Hybrid electric vehicles are another potential market, since an asymmetric capacitor can charge and discharge more rapidly than a normal battery, making it useful for regenerative braking.

Provided by Michigan Technological University (news : web)

Coffee could offer key ingredient for new treatments for Parkinson's disease

Scientists from Heptares Therapeutics have used Diamond Light Source, the UK’s national synchrotron facility, to understand the structure of a protein involved in Parkinson’s disease and other neurological disorders. Their findings, published this week in the journal Structure, could pave the way for a new generation of targeted drug treatments.

The team used Diamond’s Microfocus Macromolecular Crystallography (MX) beamline (I24) to reveal the complex structure of the vital adenosine A2A receptor and show how xanthine-based drugs such as caffeine bind to their target. Adenosine A2A receptors regulate the effects of neurotransmitters in the brain, cardiovascular and immune systems, and are of particular interest as a drug target for Parkinson’s disease. Although it was known that caffeine inhibits the action of the adenosine, the exact molecular mechanism involved was not fully understood.

“These co-structures of xanthines in complex with the adenosine A2A receptor advance our understanding of what is happening at the molecular level when the drug binds to its target and blocks the receptor’s response. Along with novel chemotypes discovered by our team, the structural data we collected at Diamond is enabling us to develop highly optimised next-generation drug candidates for Parkinson’s disease and other neurological disorders,” said Dr. Fiona Marshall, Chief Scientific Officer at Heptares.

The adenosine A2A receptor is a G-protein-coupled receptor (GPCR). GPCRs are responsible for transmitting chemical signals into a variety of different cell types. There are over 700 GPCRs encoded in the human genome and as many as 75 of these have clinical validation, presenting a wide range of opportunities as therapeutic targets in areas including cancer, diabetes, central nervous system disorders, obesity and pain.

Dr. Andrew Doré, Senior Scientist at Heptares, says: “GPCRs represent the single most important family of drug targets in the human body because they are central to so many biological processes. The design of drugs for GPCRs is hampered by the lack of structural information so access to a facility like the Diamond synchrotron is vital to our research. It has enabled us to solve the 3D structure of the adenosine A2A receptor in complex with caffeine and other xanthines as well as our own novel drug candidates.”

Caffeine is a methylxanthine, a stimulant derivative of xanthine, as is theophylline (in tea), and theobromine (in chocolate).  Methylxanthines are among the most widely consumed substances in the world. Caffeine is present in many foods and drinks and reportedly consumed at an average rate of 200mg per day by Americans (Ref. 1). In 2000, the Journal of the American Medical Association (JAMA) published research showing a correlation between higher intake of caffeine and lower incidence of Parkinson’s disease, a devastating and incurable neurological disorder (Ref. 2).

While caffeine exerts a broad range of adverse effects, and is therefore poorly suited for use as a drug, pharmaceutical researchers have generated more potent and selective adenosine receptor modulators. A2A receptor antagonists, in particular, have shown clinical efficacy in the treatment of Parkinson’s disease. First generation A2A antagonists using older furan and xanthine type chemical structures have been associated with various safety, tolerability, and pharmacokinetic limitations. Heptares have used structural information to generate the next-generation of A2A antagonists.

More information: Structure of the adenosine A2A receptor in complex with ZM241385 and the xanthines XAC and caffeine. Doré, AS et al. Structure (2011) 19, 1–11. doi:10.1016/j.str.2011.06.014

References:
Daly, GW. Caffeine analogs: biomedical impact. Cell. Mol. Life Sci. (2007) 64(16), 2153-2169
Ross, GW et al. Association of Coffee and Caffeine Intake with the Risk of Parkinson’s Disease. JAMA (2000) 283(20), 2674-2679

Provided by Diamond Light Source

New delivery system for Viagra ingredient

 

Scientists are reporting development and successful initial tests of a potential new delivery system for the biological signaling agent responsible for the effects of Viagra. It could be used to deliver the substance, called nitric oxide or NO, to treatment conditions ranging from heart disease to skin ulcers and other wounds that fail to heal, according to a report in the Journal of the American Chemical Society.

Joao Rocha and colleagues explain that NO acts as an important agent in the body for expanding blood vessels (its role in Viagra and related medicines for erectile dysfunction), preventing the formation of blood clots, aiding nerve signals, and repairing wounds. NO's multipurpose role makes it an exciting prospect for new drug development, but current NO delivery systems sometimes cause undesirable side effects. "Clearly, new materials and technologies are needed to store and target-deliver NO in biological amounts," the report notes.

The researchers developed a highly absorbent material that can carry varying amounts of NO. The material slowly releases NO at a rate that is useful for treating diseases, they conclude. More work must be done to calculate the "shelf life" of the material loaded with NO, Rocha and colleagues note, but they conclude: "This work is a first step toward assessing the real potential therapeutic applications of these materials."

More information: “Slow Release of NO by Microporous Titanosilicate ETS-4”, J. Am. Chem. Soc., 2011, 133 (16), pp 6396–6402
DOI: 10.1021/ja200663e

Abstract
A novel approach to designing nitric oxide (NO) storage and releasing microporous agents based on very stable, zeolite-type silicates possessing framework unsaturated transition-metal centers has been proposed. This idea has been illustrated with ETS-4 [Na9Si12Ti5O38(OH)·xH2O], a titanosilicate that displays excellent NO adsorption capacity and a slow releasing kinetics. The performance of these materials has been compared to the performance of titanosilicate ETS-10, [(Na,K)2Si5TiO13·xH2O], of benchmark zeolites mordenite and CaA, and of natural and pillared clays. DFT periodic calculations have shown that the presence of water in the pores of ETS-4 promotes the NO adsorption at the unsaturated (pentacoordinated) Ti4+ framework ions.

Provided by American Chemical Society (news : web)