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Saturday, May 31, 2014

20 Things You Didn't Know About... Time


The beginning, the end, and the funny habits of our favorite ticking force.

 “Time is an illusion. Lunchtime doubly so,” joked Douglas Adams in The Hitchhiker’s Guide to the Galaxy. Scientists aren’t laughing, though. Some speculative new physics theories suggest that time emerges from a more fundamental—and timeless—reality.
 Try explaining that when you get to work late. The average U.S. city commuter loses 38 hours a year to traffic delays.
 Wonder why you have to set your clock ahead in March?Daylight Saving Time began as a joke by Benjamin Franklin, who proposed waking people earlier on bright summer mornings so they might work more during the day and thus save candles. It was introduced in the U.K. in 1917 and then spread around the world.
4  Green days. The Department of Energy estimates that electricity demand drops by 0.5 percent during Daylight Saving Time, saving the equivalent of nearly 3 million barrels of oil.
5  By observing how quickly bank tellers made change, pedestrians walked, and postal clerks spoke, psychologists determined that the three fastest-paced U.S. cities are Boston, Buffalo, and New York.
 The three slowest? Shreveport, Sacramento, and L.A.
 One second used to be defined as 1/86,400 the length of a day. However, Earth’s rotation isn’t perfectly reliable. Tidal friction from the sun and moon slows our planet and increases the length of a day by 3 milli­seconds per century.
8  This means that in the time of the dinosaurs, the day was just 23 hours long.
9  Weather also changes the day. During El Niño events, strong winds can slow Earth’s rotation by a fraction of a milli­second every 24 hours.
10  Modern technology can do better. In 1972 a network of atomic clocks in more than 50 countries was made the final authority on time, so accurate that it takes 31.7 million years to lose about one second.
11  To keep this time in sync with Earth’s slowing rotation, a “leap second” must be added every few years, most recently this past New Year’s Eve.
12  The world’s most accurate clock, at the National Institute of Standards and Technology in Colorado, measures vibrations of a single atom of mercury. In a billion years it will not lose one second.
13  Until the 1800s, every village lived in its own little time zone, with clocks synchronized to the local solar noon.
14  This caused havoc with the advent of trains and timetables. For a while watches were made that could tell both local time and “railway time.”
15  On November 18, 1883, American railway companies forced the national adoption of standardized time zones.
16  Thinking about how railway time required clocks in different places to be synchronized may have inspired Einstein to develop his theory of relativity, which unifies space and time.
17  Einstein showed that gravity makes time run more slowly. Thus airplane passengers, flying where Earth’s pull is weaker, age a few extra nano­seconds each flight.
18  According to quantum theory, the shortest moment of time that can exist is known as Planck time, or 0.0000000000000000000000000000000000000000001 second.
19  Time has not been around forever. Most scientists believe it was created along with the rest of the universe in the Big Bang, 13.7 billion years ago.
20  There may be an end of time. Three Spanish scientists posit that the observed acceleration of the expanding cosmos is an illusion caused by the slowing of time. According to their math, time may eventually stop, at which point everything will come to a standstill.

Thursday, May 22, 2014

Engineers build world's smallest, fastest nanomotor: Can fit inside a single cell


Researchers at the Cockrell School of Engineering at The University of Texas at Austin have built the smallest, fastest and longest-running tiny synthetic motor to date. The team's nanomotor is an important step toward developing miniature machines that could one day move through the body to administer insulin for diabetics when needed, or target and treat cancer cells without harming good cells.
Simple nanomotor. Credit: Image courtesy of University of Texas at Austin

With the goal of powering these yet-to-be invented devices, UT Austin engineers focused on building a reliable, ultra-high-speed nanomotor that can convert electrical energy into mechanical motion on a scale 500 times smaller than a grain of salt.

Mechanical engineering assistant professor Donglei "Emma" Fan led a team of researchers in the successful design, assembly and testing of a high-performing nanomotor in a nonbiological setting. The team's three-part nanomotor can rapidly mix and pump biochemicals and move through liquids, which is important for future applications. The team's study was published in a recent issue of Nature Communications.

Fan and her team are the first to achieve the extremely difficult goal of designing a nanomotor with large driving power.

With all its dimensions under 1 micrometer in size, the nanomotor could fit inside a human cell and is capable of rotating for 15 continuous hours at a speed of 18,000 RPMs, the speed of a motor in a jet airplane engine. Comparable nanomotors run significantly more slowly, from 14 RPMs to 500 RPMs, and have only rotated for a few seconds up to a few minutes.

Looking forward, nanomotors could advance the field of nanoelectromechanical systems (NEMS), an area focused on developing miniature machines that are more energy efficient and less expensive to produce. In the near future, the Cockrell School researchers believe their nanomotors could provide a new approach to controlled biochemical drug delivery to live cells.

To test its ability to release drugs, the researchers coated the nanomotor's surface with biochemicals and initiated spinning. They found that the faster the nanomotor rotated, the faster it released the drugs.

"We were able to establish and control the molecule release rate by mechanical rotation, which means our nanomotor is the first of its kind for controlling the release of drugs from the surface of nanoparticles," Fan said. "We believe it will help advance the study of drug delivery and cell-to-cell communications."

The researchers address two major issues for nanomotors so far: assembly and controls. The team built and operated the nanomotor using a patent-pending technique that Fan invented while studying at Johns Hopkins University. The technique relies on AC and DC electric fields to assemble the nanomotor's parts one by one.

In experiments, the researchers used the technique to turn the nanomotors on and off and propel the rotation either clockwise or counterclockwise. The researchers found that they could position the nanomotors in a pattern and move them in a synchronized fashion, which makes them more powerful and gives them more flexibility.

Fan and her team plan to develop new mechanical controls and chemical sensing that can be integrated into nanoelectromechanical devices. But first they plan to test their nanomotors near a live cell, which will allow Fan to measure how they deliver molecules in a controlled fashion.


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