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Saturday, 26 July 2014

'Optical fibre' made out of thin air.

Lasers were used to create a column of low-density air surrounding a core of higher-density air that acted like a conduit to channel light (USAF)
Scientists say they have turned thin air into an 'optical fibre' that can transmit and amplify light signals without the need for any cables.
In a proof-of-principle experiment they created an "air waveguide" that could one day be used as an instantaneous optical fibre to any point on earth, or even into space.
The findings, reported in the journal Optica, have applications in long range laser communications, high-resolution topographic mapping, air pollution and climate change research, and could also be used by the military to make laser weapons.
"People have been thinking about making air waveguides for a while, but this is the first time it's been realised," says Professor Howard Milchberg of the University of Maryland, who led the research, which was funded by the US military and National Science Foundation.
Lasers lose intensity and focus with increasing distance as photons naturally spread apart and interact with atoms and molecules in the air.
Fibre optics solves this problem by beaming the light through glass cores with a high refractive index, which is good for transmitting light.
The core is surrounded by material with a lower refractive index that reflects light back in to the core, preventing the beam from losing focus or intensity.
Fibre optics, however, are limited in the amount of power they can carry and the need for a physical structure to support them.

Light and air

Milchberg and colleagues' made the equivalent of an optical fibre out of thin air by generating a laser with its light split into a ring of multiple beams forming a pipe.
They used very short and powerful pulses from the laser to heat the air molecules along the beam extremely quickly.
Such rapid heating produced sound waves that took about a microsecond to converge to the centre of the pipe, creating a high-density area surrounded by a low-density area left behind in the wake of the laser beams.
"A microsecond is a long time compared to how far light propagates, so the light is gone and a microsecond later those sound waves collide in the centre, enhancing the air density there," says Milchberg.
The lower density region of air surrounding the centre of the air waveguide had a lower refractive index, keeping the light focused.
"Any structure [even air] which has a higher density will have a higher index of refraction and thereby act like an optical fibre," says Milchberg.

Amplified signal

Once Milchberg and colleagues created their air waveguide, they used a second laser to spark the air at one end of the waveguide turning it into plasma.
An optical signal from the spark was transmitted along the air waveguide, over a distance of a metre to a detector at the other end.
The signal collected by the detector was strong enough to allow Milchberg and colleagues to analyse the chemical composition of the air that produced the spark.
The researchers found the signal was 50 per cent stronger than a signal obtained without an air waveguide.
The findings show the air waveguide can be used as a "remote collection optic," says Milchberg.
"This is an optical fibre cable that you can reel out at the speed of light and place next to [something] that you want to measure remotely, and have the signal come all the way back to where you are."
Australian expert Professor Ben Eggleton of the University of Sydney says this is potentially an important advance for the field of optics.
"It's sort of like you have an optical fibre that you can shine into the sky, connecting your laser to the top of the atmosphere," says Eggleton.
"You don't need big lenses and optics, it's already guided along this channel in the atmosphere."

Friday, 25 July 2014

Indian scientists have bred a mango that has no seed.

Seedless mangoes will be the next big thing when it comes to fruit.


Mangoes are an excellent source of calcium, vitamins A and C, antioxidants and potassium. But eating one often results in a huge mess—the seed is just too big and because of that one usually ends up with mango stains everywhere. So Indian fruit scientists came up with a solution—a sweet and juicy, seedless mango.
A team of researchers led by V.B. Patel, chairman of the Horticulture Department at the Bihar Agriculture University (BAU) in India, developed it using hybrids of the mango varieties Ratnaand Alphonso.
The seedless mango has been dubbed Sindhu and trials are underway in different locations across India, reports India Today. And it's less fibrous than regular mangoes, a yellowish pulp and weighs an average of 200 grams.
BAU’s vice chancellor M.L. Choudhary mentioned that the university has plans to make the new variety available to mango growers during the next season. “The seedless variety also has good export potential. The university would provide quality plants to mango growers in 2015 to exploit the export market,” he added.
Seedless mangoes in your local produce section? We can’t wait to taste it.

Tuesday, 25 March 2014

Solar cell emits own light source.

An overachieving material known as Perovskite could act as a solar cell by day, light source by night, scientists have found.


In an exciting solar breakthrough, scientists have discovered that a material known as Perovskite is not only capable of converting sunlight into electricity, it also emits its own light source.
The discovery was published in Nature Materials this week, and could lead to shop front signs, lamps and even mobile devices and tablets that soak up power from the Sun during the day and then light up at night.
The researchers from Nanyang Technological University in Singapore found that Perovskite, which was already one of the most promising materials for creating high-efficiency, cheap solar cells, is also highly suited for making lasers of different frequencies. The material is five times cheaper than current silicon-based solar cells.
In a press release, physicist Sum Tze Chien explained that he made the disovery by chance when he asked his postdoc Xing Guichuan to shine a laser on a new hybrid Perovskite solar cells they're currently developing and they started glowing brightly.
“By tuning the composition of the material, we can make it emit a wide range of colours, which also makes it suitable as a light emitting device, such as flat screen displays.”

Tuesday, 4 March 2014

A Solar-Powered Drone Designed To Fly For Five Years Nonstop

Titan Aerospace will test a drone that could track hurricanes, spot pirates, and more.

If a drone never had to land, it could track hurricanes, spot pirates and smugglers, follow animal migrations, and even act as an auxiliary GPS. In essence, it would be a geostationary satellite without the expense of going to space. Later this year, the company Titan Aerospace will test a drone that could do just that. The Solara 50, named for its 50-meter wingspan, will fly at 65,000 feet—above most other aircraft and above weather that could disturb its flight and block the sun, its source of power. Titan will market it as an “atmospheric satellite."
Don't believe us? Watch the video below.


Tuesday, 18 February 2014

Single chip device to provide real-time 3-D images from inside the heart, blood vessels.

A single-chip catheter-based device that would provide forward-looking, real-time, three-dimensional imaging from inside the heart, coronary arteries and peripheral blood vessels is shown being tested.

Researchers have developed the technology for a catheter-based device that would provide forward-looking, real-time, three-dimensional imaging from inside the heart, coronary arteries and peripheral blood vessels. With its volumetric imaging, the new device could better guide surgeons working in the heart, and potentially allow more of patients' clogged arteries to be cleared without major surgery.

The device integrates ultrasound transducers with processing electronics on a single 1.4 millimeter silicon chip. On-chip processing of signals allows data from more than a hundred  on the device to be transmitted using just 13 tiny cables, permitting it to easily travel through circuitous blood vessels. The forward-looking images produced by the device would provide significantly more information than existing cross-sectional ultrasound.
Researchers have developed and tested a prototype able to provide image data at 60 frames per second, and plan next to conduct animal studies that could lead to commercialization of the device.
"Our device will allow doctors to see the whole volume that is in front of them within a blood vessel," said F. Levent Degertekin, a professor in the George W. Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. "This will give cardiologists the equivalent of a flashlight so they can see blockages ahead of them in occluded arteries. It has the potential for reducing the amount of surgery that must be done to clear these vessels."
Details of the research were published online in the February 2014 issue of the journal IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. Research leading to the device development was supported by the National Institute of Biomedical Imaging and Bioengineering (NIBIB), part of the National Institutes of Health.
This is a single-chip catheter-based device that would provide forward-looking, real-time, three-dimensional imaging from inside the heart, coronary arteries and peripheral blood vessels is shown on the tip of a finger. A microscope image of the device is shown behind it.

"If you're a doctor, you want to see what is going on inside the arteries and inside the heart, but most of the devices being used for this today provide only cross-sectional images," Degertekin explained. "If you have an artery that is totally blocked, for example, you need a system that tells you what's in front of you. You need to see the front, back and sidewalls altogether. That kind of information is basically not available at this time."
The single chip device combines capacitive micromachined ultrasonic transducer (CMUT) arrays with front-end CMOS electronics technology to provide three-dimensional intravascular ultrasound (IVUS) and intracardiac echography (ICE) images. The dual-ring array includes 56 ultrasound transmit elements and 48 receive elements. When assembled, the donut-shaped array is just 1.5 millimeters in diameter, with a 430-micron center hole to accommodate a guide wire.
Power-saving circuitry in the array shuts down sensors when they are not needed, allowing the device to operate with just 20 milliwatts of power, reducing the amount of heat generated inside the body. The ultrasound transducers operate at a frequency of 20 megahertz (MHz).
Imaging devices operating within blood vessels can provide higher resolution images than devices used from outside the body because they can operate at higher frequencies. But operating inside  requires devices that are small and flexible enough to travel through the circulatory system. They must also be able to operate in blood.
Doing that requires a large number of elements to transmit and receive the ultrasound information. Transmitting data from these elements to external processing equipment could require many cable connections, potentially limiting the device's ability to be threaded inside the body.
Degertekin and his collaborators addressed that challenge by miniaturizing the elements and carrying out some of the processing on the probe itself, allowing them to obtain what they believe are clinically-useful images with only 13 cables.
"You want the most compact and flexible catheter possible," Degertekin explained. "We could not do that without integrating the electronics and the imaging array on the same chip."
Based on their prototype, the researchers expect to conduct animal trials to demonstrate the device's potential applications. They ultimately expect to license the technology to an established medical diagnostic firm to conduct the clinical trials necessary to obtain FDA approval.
For the future, Degertekin hopes to develop a version of the device that could guide interventions in the heart under magnetic resonance imaging (MRI). Other plans include further reducing the size of the device to place it on a 400-micron diameter guide wire.