Batteries that can be printed onto a surface with “nanotube ink“ have been demonstrated by US researchers, who say the technique will fit well within the growing field of printed electronics, which still use conventional power sources.
The batteries were created by George Gruner and colleagues at the University of California in Los Angeles and use the same zinc-carbon chemistry as ordinary non-rechargeable batteries, according to Newscientist.com.
Being able to print flexible batteries onto different surfaces should prove handy for powering disposable devices, such as long-range RFID tags or small displays, the researchers say.
The batteries are made from two layers containing carbon nanotubes and a third layer of zinc foil, and are less than a millimetre thick.
A great many carbon nanotubes can be packed into these layers. They form randomly aligned nanotube networks that conduct charge more efficiently than the metals normally used--connecting many points in the battery simultaneously, without hampering the electrochemical process that generates power.
To make the battery, a layer of nanotubes is first deposited in the form of “nanotube ink“ onto a surface. This layer acts as the charge collector, which removes current from the battery.
Next, a layer of nanotube ink mixed with manganese oxide powder and electrolytes, which carries charge within the cell, is applied on top. This layer acts as the cathode. Finally, a piece of zinc foil--the anode--is applied.
“The batteries are similar to conventional batteries,“ says Gruner, “with the electrically conducting nanoscale networks replacing conventional metals and electrodes.“
He adds that the designs should make it possible to get more power than a conventional design would from the same materials, , “an important factor for portable electronics applications.“
The researchers also made supercapacitors using the inking technique and plan to combine these with batteries for applications requiring more power.
Furthermore, since both printed batteries and supercapacitors can be made entirely at room temperature, it should be possible to mass-produce them using established printing methods, Gruner says.
Chemist George Chen at Nottingham University, UK, agrees that nanotubes could provide ways to improve battery performance. But he points out that Gruner’s batteries were only tested at low power. “The discharge currents are, so far, smaller than needed for practical use.“

Plasma antennas behave much like solid metal antennas because electrons flow freely in the hot gas, just as they do in metal conductors.

A new antenna made of plasma (a gas heated to the point that the electrons are ripped free of atoms and molecules) works just like conventional metal antennas, except that it vanishes when you turn it off.
That’s important on the battlefield and in other applications where antennas need to be kept out of sight. In addition, unlike metal antennas, the electrical characteristics of a plasma antenna can be rapidly adjusted to counteract signal jamming attempts, ScienceDaily reported.
Plasma antennas behave much like solid metal antennas because electrons flow freely in the hot gas, just as they do in metal conductors. But plasmas only exist when the gasses they’re made of are very hot.
The moment the energy source heating a plasma antenna is shut off, the plasma turns back into a plain old (non conductive) gas. As far as radio signals and antenna detectors go, the antenna effectively disappears when the plasma cools down.
The antenna design being presented at the APS Division of Plasma Physics meeting in Orlando consists of gas-filled tubes reminiscent of neon bulbs. The physicists presenting the design propose that an array of many small plasma elements could lead to a highly versatile antenna that could be reconfigured simply by turning on or off various elements.

A new antenna made of plasma (a gas heated to the point that the electrons are ripped free of atoms and molecules) works just like conventional metal antennas, except that it vanishes when you turn it off.
That’s important on the battlefield and in other applications where antennas need to be kept out of sight. In addition, unlike metal antennas, the electrical characteristics of a plasma antenna can be rapidly adjusted to counteract signal jamming attempts, ScienceDaily reported.
Plasma antennas behave much like solid metal antennas because electrons flow freely in the hot gas, just as they do in metal conductors. But plasmas only exist when the gasses they’re made of are very hot.
The moment the energy source heating a plasma antenna is shut off, the plasma turns back into a plain old (non conductive) gas. As far as radio signals and antenna detectors go, the antenna effectively disappears when the plasma cools down.
The antenna design being presented at the APS Division of Plasma Physics meeting in Orlando consists of gas-filled tubes reminiscent of neon bulbs. The physicists presenting the design propose that an array of many small plasma elements could lead to a highly versatile antenna that could be reconfigured simply by turning on or off various elements.

Scientists have found a naturally occurring protein can protect against heart cell damage after a heart attack.
Nerve growth factor (NGF) was thought to act only on nerve cells in the body, but mounting evidence suggests it acts on heart muscle cells too, BBC reported.
A Bristol Heart Institute team tested NGF in rats and this had promising results, Cell Death and Differentiation journal reports.
They are hopeful that the treatment would also benefit humans.
Heart disease is the most common cause of death in the UK. In 2004, there were about 231,000 new heart attacks.
Heart attacks happen when one of the coronary arteries carrying oxygen-rich blood to the heart muscle is blocked.
If the blood supply is cut off, a part of the heart muscle dies. And this can lead to complications such as heart failure.
Drugs are already available to help prevent and minimize the damage caused by a heart attack.
These include aspirin, which works by thinning the blood to improve blood flow, and clot-busting drugs called thrombolytics to dissolve clots in the artery.
Dr Costanza Emanueli and her colleagues found that injecting the gene for NGF into the hearts of rats having a heart attack stopped heart cells dying off.
Dr Emanueli said: “This is the first time that a pro-survival effect of NGF in the heart has been found.
“Some other growth factors are already used clinically to treat different diseases, and our study shows that NGF may be a novel way of protecting the heart from further damage following a heart attack.“
Professor Jeremy Pearson of the British Heart Foundation, which provided funding for the work, said: “Dr Emanueli’s research opens up the exciting and unexpected possibility of helping to repair damaged hearts by using a natural factor previously only thought to help nerves grow.“

Contrary to what one might expect, the hormone melatonin--which helps regulate sleep cycles in humans and other animals--might actually disrupt memory formation, suggests a study in fish.
Zebrafish exposed to melatonin take four times longer to recall a learned behavior than usual, researchers report.
The scientists do not know whether melatonin supplements have a negative impact on memory in people, but they believe more research into this hormone pathway is necessary. They add that a drug that blocks the influence of melatonin improved memory in the zebrafish when given at night, Telegraph.co.uk said.
Zebrafish can retain information for days, according to Gregg Roman at the University of Houston, Texas, US. So Roman and his colleagues trained these fish to follow the path of a moving light source beamed through the side of the tank.
Fish typically have an instinct to swim away from light--but in this experiment they received a mild shock when they did so. On average, it took the fish about 20 minutes to learn to stick close to the light. More importantly, when they were re-tested a day later, the zebrafish still remembered that they needed to keep close to the light.
But when Roman and his teammates added melatonin to the water, the fish had a tougher time remembering to follow the light. In fact, they were four times slower to recall this lesson than their control counterparts.
Researchers speculate that melatonin might somehow interfere with memory formation in fish by disrupting the animals’ internal body clock. Levels of circulating melatonin--which gets released by the pineal gland in the brains of both fish and humans--peak at night, thereby helping to regulate sleep cycles.
Roman says that melatonin receptors on the outside of nerve cells might indirectly influence the long-term wiring of memory networks in the brain.
He stresses that fish and humans have some overlapping biochemical signaling pathways. But he says it is unclear whether the melatonin supplements that people take for jet lag and a type of winter depression called seasonal affective disorder (SAD) also influence memory formation.

When cockroaches have a choice of two or more shelters under which to settle, their decision is influenced by the number of cockroaches already there.

Scientists have designed tiny robots that can mingle with a social group of cockroaches and influence their behavior.
They say that similar robots will help them to unpick the decision-making processes in other gregarious species that carry out ’collective behaviors’ such as deciding where to rest or selecting food sources, Nature.com reported.
Unlike ants and bees, cockroaches do not have a sophisticated social structure, but they do take notice of what their fellows are doing. Last year Jose Halloy, a theoretical biologist at the Free University of Brussels, Belgium, reported that when cockroaches have a choice of two or more shelters under which to settle, their decision is influenced by the number of cockroaches already there.
In that study, the researchers placed up to a hundred cockroaches in an arena and found they were more likely to stop at one shelter if another cockroach was already there--and highly likely to stop if several were there.
This accelerating pace of social gathering stopped sharply when the shelter became full--the cockroaches sensed the overcrowding and scurried elsewhere.
The scientists deduced the straightforward, but non-linear, mathematical relationship influencing an individual cockroach’s decision to follow or deviate from its general inclination to shelter in the dark.
For the new study, Halloy commissioned colleagues at the Swiss Federal Institute of Technology in Lausanne, Switzerland, to make cockroach-size robots based on this algorithm. His team built a simple one-meter diameter plastic arena containing two 155-centimetre diameter shelters, like beach umbrellas, for a series of trials on a community of four robots and 12 cockroaches. One shelter was darker than the other.
First they had to make the robots--which the cockroaches initially ignored or avoided--accepted members of the cockroach community. Because the insects recognize each other through the pheromones they release, the scientists collected the odorous chemicals from males and wrapped the robots in blotting paper containing a drop equivalent to the scent of one cockroach. So treated, they were accepted as fellow insects.
Cockroaches are nocturnal and so always prefer to rest in the dark, a tactic that keeps them out the way of predators such as humans. When the robots were programmed to have the same preference for darker corners, the real insects congregated in the dark shelter in three-quarters of the trials.
But when the robots were programed to prefer light places, the insects congregated in the lighter shelter in about 60 percent of trials. The presence of just a few robots with contrary ’instincts’ was enough to override the natural preferences of cockroaches, notes Halloy.

A bat's 'noseleaf' is capable of emitting sonar in different ways depending on the frequency.

How, exactly, does a bat shoot sonar beams out of its nose? Rolf Muller, a computational physicist at Shandong University in Jinan, China, has combed the caves of Southeast Asia to find out. “We are looking at different species to understand their physical tricks,“ says Muller, who models the way that bat noses act like antenna, and how their ears work as dishes to collect sound.
The work matters not just to biophysicists who want to understand how animals evolve complex systems, but also to roboticists trying to find new ways of navigating in situations in which light sensors don’t work so well, including at night or underwater, Nature.com said.
Few biophysical studies of bat noses have been done. One researcher bent back a bat’s noseleaf--the complex structure surrounding its nostrils--to see what would happen; another scientist smeared the delicate structures with petroleum jelly. Both procedures messed up the bats’ navigation.
To get a better picture of what’s going on in a bat nose, Muller took X-ray scans of the face of a Rufous horseshoe bat (Rhinolophus rouxii ), compiling scans to build a three-dimensional computer model of the nose cavities. He then shot sound waves of differing frequencies through the modeled nose to see where they resonated, and how they were emitted from the noseleaf.
High frequency sounds, Muller found, resonated in a structure in the middle-back of the nose called the sella, and were emitted from the noseleaf as a narrowly focused beam. Low-frequency sounds resonated in a cavity called the lancet, at the top of the noseleaf. Furrows in the lancet created four secondary sound sources, so that sonar was emitted from a total of six sources, rather than just the two nostril holes. “It widens the beam--you have a wider array and you can splash the sound around better,“ says Muller.
The wide beam might be useful for general navigation, Muller says. A tighter shot of sonar would be better for chasing prey or avoiding specific objects, for instance.
Sonar has long been used as a basic navigational tool in robots. Making a noise and listening for its reflection with a microphone can help to determine distances to objects and their locations.
Sonar is generally slower to interpret and less precise than computer vision or laser sensors. But that’s a problem that bats have managed to work around, says Herbert Peremans, a roboticist at the University of Antwerp in Belgium.

What goes around comes around. Unfortunately, no such karma figures in plans to deflect asteroids on a collision course with Earth, a hearing of the US House Science and Technology Committee was told last week. One big whack will deflect an asteroid temporarily, but does not guarantee safety next time its orbit brings it close.
According to Newscientist.com asteroid researchers have long debated the merits of deflecting asteroids with a powerful blast such as a nuclear explosion. However, Rusty Schweickart, who heads an asteroid research group called the B612 Foundation, told the committee that the effects of powerful blasts are hard to predict, especially if Earth’s gravitational pull acts on the object. An asteroid could pass through one of the “keyholes“ that would nudge it back onto a collision course, so once diverted it might need to be steered past Earth to prevent this.
At the same hearing, members attacked NASA for ignoring smaller asteroids.