Sheets of Virus Generate Electricity when Squished

Pressing a virus-filled device can generate power. (The gloves protect the virus, which only infects bacteria, from us.)

lbl.gov

Squishing a stack of virus sheets generates enough electricity to power a small liquid crystal display. With increased power output, these virus films might one day use the beating of your heart to power a pacemaker, the researchers behind them say.

Piezoelectric materials build up charge when pushed or squeezed. These materials may be familiar to you: they generate the spark in a gas lighter, and motors powered by such materials vibrate some cell phones. Piezoelectric materials made of metals or polymers require large inputs of energy to build up a charge. Bone, DNA, and protein fibers are weakly piezoelectric, but it’s hard to efficiently organize these materials on a large scale to yield electricity.

To handle this organizational issue, Seung-Wuk Lee, of the University of California in Berkeley and the Lawrence Berkeley National Laboratory, and his colleagues looked for a biomaterial that had intrinsic order and was easy to make. They settled on the M13 bacteriophage, a rod-shaped virus that only infects bacteria. One bacterium can produce one million copies of the virus within four hours, so starting material isn't a problem. And the virus neatly arranges itself in stacked rows when spread on a surface.

New electrode material could lead to powerful rechargeable sodium batteries

A new electrode material could help make lightweight, powerful rechargeable sodium batteries to replace lithium-ion batteries used in electronics and some electric vehicles. The material contains widely available iron, instead of the nickel and cobalt commonly used in these electrodes, and enables a similar energy density to electrodes in lithium batteries.

Sodium is an attractive candidate to replace lithium in batteries because it’s cheaper and widely available around the world. But building a sodium battery requires redesigning battery technology to accommodate the chemical reactivity and larger size of sodium atoms.

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New electrode material could lead to rechargeable sodium batteries

A typical lithium battery, showing ions stored at each electrode.

Photograph by Argonne National Laboratory

A rechargeable battery, whether lithium or sodium, contains two electrodes, the anode and the cathode. When a battery with an anode made from sodium metal discharges, electrons flow from that electrode to the other. The anode sloughs off positively charged sodium ions, which travel over to the cathode and wiggle inside the material to balance the extra negative charges coming in through the circuit.

Composite material brings metal-air batteries a step closer

As a society, we are now heavily dependent on good battery technology. Indeed, as climate change starts to bite and hydrocarbon fuels become more expensive, the demand for better batteries is just going to increase. But the current best technology is simply not going to keep pace. Commercial Lithium ion batteries are approaching their theoretical maximum energy storage density, which is lower than that of gasoline by a factor of about 60-70. In the meantime, we want electric cars like the Tesla—but lighter, with longer range and faster recharging times.

One solution to some of these problems may be metal-air batteries. These batteries have maximum energy densities approaching that of gasoline. Better than that, they should be simpler to construct and could even be made from cheaper materials. In other words, when viewed through rose-tinted glasses, metal-air batteries are better in every way.

The problem is that no one knows how to make one that meets all of these criteria. A group of chemists from University of Waterloo in Canada may be heading in the right direction, though.

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Etc: The original paper describing the Calvin cycle of photosynthesis contained a diagram of the equipment used to study it—complete with a stick-figure fisherman that slipped past reviewers.

The original paper describing the Calvin cycle of photosynthesis contained a diagram of the equipment used to study it—complete with a stick-figure fisherman that slipped past reviewers.

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Making a material transparent in order to visualize its internal energy states

In the world of physics, there is nothing with higher geek credibility than making a normally opaque object appear transparent. One of the first examples of this was something called electromagnetically induced transparency (EIT). This basically involves shining one light beam on a substance to modify it in a way that allows a different light beam to pass through unhindered.

Now, the cool thing about this is that it depends on the details of the atomic or molecular structure of the substance. Which means that, aside from letting physicists do EIT party tricks, it can be used as a sensitive probe that can separate nearly identical substances from one another.

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Light-switched local anaesthetic lets scientists turn pain nerves on and off

Local anaesthetics have been used in the clinic for well over a century. Cocaine was the first drug to be used to block sensory nerves, but was fairly quickly superseded by a number of synthetic alternatives that don't have the pesky side effects of inducing euphoria or being highly addictive. Local anaesthetics work by blocking the flow of sodium ions across neuronal cell membranes, blocking the transmission of electrical signals. Unfortunately, they can be fairly long lasting and not particularly selective, as you might have noticed if you've ever attempted to drink something following a visit to the dentist.

A new option has been described in Nature Methods, developed by a group of researchers at UC Berkeley, the University of Munich and the University of Bordeaux. The group describes a novel local anaesthetic that can be switched on and off using different wavelengths of light, potentially allowing much finer control of exactly which nerves it blocks.

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Revenge is ours: extracting energy from a cockroach

I love science. The joy of discovery in pure research combines with applied science to leave me fantasizing about future technology. Add in the occasional WTF moment and the comedy inherent in poorly prepared presentations, and you have the perfect occupation. Unfortunately, science sometimes attracts people who pull the wings off a cockroach, pin it on its back, and stick electrodes inside it to use it as a mini-electricity generator.

Now, I hate cockroaches as much as anyone, and there is a certain satisfaction in extracting revenge for all those restless nights in rooms that, shall we say, rustled, but... Surely there was a good reason for this?

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Reverse alchemy: replacing precious platinum with ignoble iron

Homogeneous catalysis, in which the catalyst is mixed directly in with the reaction components, sees widespread use in industrial settings. The catalysts themselves are often complex organometallic compounds that contain a precious metal atom/ion—platinum, rhodium, palladium, rhenium—at their molecular center.

From an engineering standpoint, a reactor for a homogeneously catalyzed reaction can often be described as a catalyst recovery system first, reactor second. The high cost of these precious metals means that recovery and reuse of the catalyst is essential to making the reactions economic.

A report published in last week's edition of Science discusses the work of a team of chemists who are looking at ways of obviating the need for the precious metals, replacing them with their more ordinary relatives. The paper focuses on chemistry that is important to the silicone industry.

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New membrane can block helium, yet allow water to flow freely

Membranes and barriers are used all the time in industrial and lab settings, and you may even have a few of them around the home. They can help keep materials apart that need to be separated, or can selectively allow certain materials to mix while holding others back. Graphene, the two-dimensional hexagonal lattice of carbon, is thought to be completely impermeable to all gases and liquids. That would obviously make it an extremely effective barrier film.

Creating sufficient quantities of pure graphene is not an an easy task, but graphene oxide (GO) films can be readily made in the lab. There's a paper in last week's edition of Science that examines the properties of graphene oxide films.

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