Net World
Directory listing

Home
Auctions
Autos
Best 1000 sites
Computers
Countries
Entertainment
Games
Health
Jobs
News
Online shopping
Recreation
Search
Sports
Travel
Suggestions
Contact us
  Net World Directory

Your personal directory for the internet
 
   
      Net World Directory: Archives of technology blog
light.jpg
 

Archives Of Technology Blog From Networlddirectory


Subscribe To Technology Blog RSS Feed  RSS content feed What is RSS feed?



July 14, 2008, 4:42 PM CT

Physicists tweak quantum force

Physicists tweak quantum force
A scanning electron micrograph, taken with an electron microscope, shows the comb-like structure of a metal plate at the center of newly published University of Florida research on quantum physics.

Yiliang Bao and Jie Zoue/University of Florida
Cymbals don't clash of their own accord - in our world, anyway.

But the quantum world is bizarrely different. Two metal plates, placed almost infinitesimally close together, spontaneously attract each other.

What seems like magic is known as the Casimir force, and it has been well-documented in experiments. The cause goes to the heart of quantum physics: Seemingly empty space is not actually empty but contains virtual particles linked to fluctuating electromagnetic fields. These particles push the plates from both the inside and the outside. However, only virtual particles of shorter wavelengths - in the quantum world, particles exist simultaneously as waves - can fit into the space between the plates, so that the outward pressure is slightly smaller than the inward pressure. The result is the plates are forced together.

Now, University of Florida physicists have found they can reduce the Casimir force by altering the surface of the plates. The discovery could prove useful as tiny "microelectromechanical" systems - so-called MEMS devices that are already used in a wide array of consumer products - become so small they are affected by quantum forces.

"We are not talking about an immediate application," says Ho Bun Chan, an assistant professor of physics and the first author of a paper on the findings that appears today in the online edition of the journal Physical Review Letters.........

Posted by: Kevin      Read more         Source


July 10, 2008, 8:26 PM CT

A Colorful Approach to Solar Energy

A Colorful Approach to Solar Energy
Revisiting a once-abandoned technique, engineers at the Massachusetts Institute of Technology (MIT) have successfully created a sophisticated, yet affordable, method to turn ordinary glass into a high-tech solar concentrator.

The technology, which uses dye-coated glass to collect and channel photons otherwise lost from a solar panel's surface, could eventually enable an office building to draw energy from its tinted windows as well as its roof.

Electrical engineer Marc Baldo, his graduate students Michael Currie, Jon Mapel and Timothy Heidel, and postdoctoral associate Shalom Goffri, announced their findings in the July 11 issue of Science.

"We think this is a practical technology for reducing the cost of solar power," said Baldo.

The scientists coated glass panels with layers of two or more light-capturing dyes. The dyes absorbed incoming light and then re-emitted the energy into the glass, which served as a conduit to channel the light to solar cells along the panels' edges. The dyes can vary from bright colors to chemicals that are mostly transparent to visible light.

Because the edges of the glass panels are so thin, far less semiconductor material is needed to collect the light energy and convert that energy into electricity.........

Posted by: Kevin      Read more         Source


July 9, 2008, 9:19 PM CT

Controlling the Size of Nanoclusters

Controlling the Size of Nanoclusters
Michael White and Melissa Patterson review an image of a molybdenum sulfide nanocluster. (Click image to download hi-res version.)
Scientists from the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and Stony Brook University have developed a new instrument that allows them to control the size of nanoclusters - groups of 10 to 100 atoms - with atomic precision. They created a model nanocatalyst of molybdenum sulfide, the first step in developing the next generation of materials to be used in hydrodesulfurization, a process that removes sulfur from natural gas and petroleum products to reduce pollution.

As published in the July 9, 2008 online edition of the Journal of Physical Chemistry C, the researchers made size-selected molybdenum sulfide nanoclusters as gaseous ions, and then gently deposited the clusters on a gold surface. The nanoclusters interact weakly with the gold support and therefore remain intact.

"With this new instrument, we can control how a number of and what type of atoms are in a nanocluster," said Brookhaven chemist Michael White, the principal author of the paper. "This knowledge enables us to make nanoclusters with predetermined size, structure and chemical composition, all which are important for the design of new catalysts."

Currently, molybdenum sulfide nanoparticles are used for hydrodesulfurization and other chemical processes, but it is not known what size is most active or how the reactions occur on small particles. The ability to make model nanocatalysts containing molybdenum sulfide particles of variable size and chemical makeup will allow White and coworkers to understand how current catalysts work and help design the next generation of catalysts.........

Posted by: Kevin      Read more         Source


June 26, 2008, 8:50 PM CT

New Nano Technique Significantly Boosts Boiling Efficiency

New Nano Technique Significantly Boosts Boiling Efficiency
Whoever penned the old adage "a watched pot never boils" surely never tried to heat up water in a pot lined with copper nanorods.

A new study from scientists at Rensselaer Polytechnic Institute shows that by adding an invisible layer of the nanomaterials to the bottom of a metal vessel, an order of magnitude less energy is mandatory to bring water to boil. This increase in efficiency could have a big impact on cooling computer chips, improving heat transfer systems, and reducing costs for industrial boiling applications.

"Like so a number of other nanotechnology and nanomaterials breakthroughs, our discovery was completely unexpected," said Nikhil A. Koratkar, associate professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer, who led the project. "The increased boiling efficiency seems to be the result of an interesting interplay between the nanoscale and microscale surfaces of the treated metal. The potential applications for this discovery are vast and exciting, and we're eager to continue our investigations into this phenomenon."

Bringing water to a boil, and the related phase change that transforms the liquid into vapor, requires an interface between the water and air. In the example of a pot of water, two such interfaces exist: at the top where the water meets air, and at the bottom where the water meets tiny pockets of air trapped in the microscale texture and imperfections on the surface of the pot. Even though most of the water inside of the pot has reached 100 degrees Celsius and is at boiling temperature, it cannot boil because it is surrounded by other water molecules and there is no interface - i.e., no air - present to facilitate a phase change.........

Posted by: Kevin      Read more         Source


June 26, 2008, 8:42 PM CT

Quantum computing breakthrough

Quantum computing breakthrough
A new hybrid atom
The odd behavior of a molecule in an experimental silicon computer chip has led to a discovery that opens the door to quantum computing in semiconductors.

In a Nature Physics journal paper currently online, the scientists describe how they have created a new, hybrid molecule in which its quantum state can be intentionally manipulated - a mandatory step in the building of quantum computers.

"Up to now large-scale quantum computing has been a dream," says Gerhard Klimeck, professor of electrical and computer engineering at Purdue University and associate director for technology for the national Network for Computational Nanotechnology.

"This development may not bring us a quantum computer 10 years faster, but our dreams about these machines are now more realistic".

The workings of traditional computers haven't changed since they were room-sized behemoths 50 years ago; they still use bits of information, 1s and 0s, to store and process information. Quantum computers would harness the strange behaviors found in quantum physics to create computers that would carry information using quantum bits, or qubits. Computers would be able to process exponentially more information.

If a traditional computer were given the task of looking up a person's phone number in a telephone book, it would look at each name in order until it found the right number. Computers can do this much faster than people, but it is still a sequential task. A quantum computer, however, could look at all of the names in the telephone book simultaneously.........

Posted by: Kevin      Read more         Source


June 26, 2008, 8:25 PM CT

3-D Nanostructures with Magnetic Materials

3-D Nanostructures with Magnetic Materials
Working in the trenches: Transmission electron microscopy image of a thin cross section of 160 nanometer trenches shows deposited nickel completely filling the features without voids. (Color added for clarity.)
Materials researchers at the National Institute of Standards and Technology (NIST) have developed a process to build complex, three-dimensional nanoscale structures of magnetic materials such as nickel or nickel-iron alloys using techniques compatible with standard semiconductor manufacturing. The process, described in a recent paper,* could enable whole new classes of sensors and microelectromechanical (MEMS) devices.

The NIST team also demonstrated that key process variables are associated with relatively quick and inexpensive electrochemical measurements, pointing the way to a fast and efficient way to optimize the process for new materials.

The NIST process is a variation of a technique called "Damascene metallization" that often is used to create complicated three-dimensional copper interconnections, the "wiring" that links circuit elements across multiple layers in advanced, large-scale integrated circuits. Named after the ancient art of creating designs with metal-in-metal inlays, the process involves etching complex patterns of horizontal trenches and vertical "vias" in the surface of the wafer and then uses an electroplating process to fill them with copper. The high aspect ratio features may range from tens of nanometers to hundreds of microns in width. Once filled, the surface of the disk is ground and polished down to remove the excess copper, leaving behind the trench and via pattern.........

Posted by: Kevin      Read more         Source


June 23, 2008, 8:01 PM CT

A look into the nanoscale

A look into the nanoscale
A visible light laser beam (i) is focused onto the sample (iii) and acts as the excitation pulse. A soft X-ray pulse (ii) is focused to the same location but at a continuously variable delay. The X-ray pulse diffracts from the sample, carrying information about the transient sample structure to the CCD detector (v) in the form of a coherent diffraction pattern. A mirror (iv) separates the direct beam from the diffracted light: the direct FEL beam (vi) passes straight through a hole in the mirror and is not detected in the CCD image.
Lawrence Livermore National Laboratory scientists have captured time-series snapshots of a solid as it evolves on the ultra-fast timescale.

Using femtosecond X-ray free electron laser (FEL) pulses, the team, led by Anton Barty, is able to observe condensed phase dynamics such as crack formation, phase separation, rapid fluctuations in the liquid state or in biologically relevant environments.

Other Livermore researchers include Michael Bogan, Stafan Hau-Riege, Stefano Marchesini, Matthias Frank, Bruce Woods, former Livermore researcher Saša Bajt and former LLNL scientist Henry Chapman, who is now at the Centre for Free Electron Laser Science, DESY, in Hamburg, Gera number of.

"The ability to take images in a single shot is the key to studying non-repetitive behavior mechanisms in a sample," Barty said.

As the femtosecond laser blasts the sample, it is destroyed, but not before the researchers created images with a 50-nanometer spatial resolution, and a 10-femtosecond shutter speed. (A femtosecond is one billionth of one millionth of a second. For context, a femtosecond is to a second as a second is to about 32 million years.).

"This experiment opens the door to a new regime of time-resolved experiments in mesoscopic dynamics," Barty said. "This technique could be extended to a few nanometers spatial and a few tens of femtoseconds temporal resolution".........

Posted by: Kevin      Read more         Source


June 23, 2008, 7:19 PM CT

Light-Driven Reversible Nanoswitches

Light-Driven Reversible Nanoswitches
Credit: Paul Weiss lab, Penn State

Illustration of the light-activated switch made by the Paul Weiss lab at Penn State. A bridge within the azobenzene molecule, made by two double-bonded nitrogen atoms, each also bound to a benzene ring, reconfigures when the molecule absorbs light. The two benzene rings move to the same side of the molecule (cis configuration) when exposed to ultraviolet light, and to opposite sides (trans configuration) when exposed to visible light.
The ability to see is based on molecules in the eye that flip from one conformation to another when exposed to visible light. Now, a new technique for attaching light-sensitive organic molecules to metal surfaces allows the molecules to be switched between two different configurations in response to exposure to different wavelengths of light. Because the configuration changes are reversible and can be controlled without direct contact, this technique could enable applications that can be controlled at the molecular scale.

The technology has been suggested as a possible basis for molecular motors, artificial muscles, and molecular electronics. The research results, obtained by a team led by Paul S. Weiss, distinguished professor of chemistry and physics at Penn State University and James M. Tour, Chao professor of chemistry at Rice University, are published in the June 2008 issue of the journal Nano Letters.

Until now, progress was impeded because, when such molecules were attached to surfaces, they no longer could be switched back and forth, as they could be when they were in solution. The new technique uses a change in the shape of an azobenzene molecule in response to light to provide two different states. The azobenzene molecule consists of a bridge of two nitrogen atoms attached to one another by a double bond, with each nitrogen atom also bound to a benzene ring. The two benzene rings can be on the same side of the molecule (cis configuration) or on opposite sides (trans configuration). When the molecule absorbs energy, in the form of light, it can change between cis and trans configurations in a process called photoisomerization. "This mechanism is essentially the same that we use in our eyes for vision," said Weiss. "The molecule responds to light by making a change that can be harnessed. In the eye, the change causes a neural impulse".........

Posted by: Kevin      Read more         Source


June 9, 2008, 8:43 PM CT

Interfering with the Global Positioning System

Interfering with the Global Positioning System
You can't always trust your GPS gadget. As researchers have long known, perplexing electrical activity in the upper atmospheric zone called the ionosphere can tamper with signals from GPS satellites.

Now, new research and monitoring systems are clarifying what happens to disruptive clouds of electrons and other electrically charged particles, known as ions, in the ionosphere. The work may lead to regional predictions of reduced GPS reliability and accuracy.

One team of scientists has recently observed Earth's aurora, which is a prominent manifestation of ionospheric electrical activity, in the act of disrupting GPS equipment. Other researchers have successfully tested a way to forecast GPS disturbances for marine users, with likely extension to users on land.

Some research groups are turning the tables and employing GPS receivers as tools with which to conduct basic research on the electrical-current structures of the ionosphere.

The scientific reports on these and other recent developments are available in a special section of Space Weather: The International Journal of Research and Applications, a publication of the American Geophysical Union, or AGU.

A magazine-style article that introduces the section was posted online Friday, June 6. It summarizes past research and operational developments regarding ionospheric effects on GPS, and discusses potential future improvements in the field.........

Posted by: Jim      Read more         Source


June 4, 2008, 10:49 PM CT

Prototype Hydrogen Storage Tank

Prototype Hydrogen Storage Tank
Salvador Aceves (left) and Tim Ross check out the on-board hydrogen storage tank that powers a prototype hybrid vehicle.
Photos by Jacqueline McBride/LLNL
A cryogenic pressure vessel developed and installed in an experimental hybrid vehicle by a Lawrence Livermore National Laboratory research team can hold liquid hydrogen for six days without venting any of the fuel.

Unlike conventional liquid hydrogen (LH2 tanks in prototype cars, the LLNL pressure vessel was parked for six days without venting evaporated hydrogen vapor.

The LLNL development has significantly increased the amount of time it takes to start releasing hydrogen during periods of long-term parking, as in comparison to today's liquid hydrogen tanks capable of holding hydrogen for merely two to four days.

LH2 tanks hold super-cold liquid hydrogen at around -420 Fahrenheit. Like water boiling in a tea kettle, pressure builds as heat from the environment warms the hydrogen inside. Current automotive LH2 tanks must vent evaporated hydrogen vapor after being parked three to four days, even when using the best thermal insulation available (200 times less conductive than Styrofoam insulation).

In recent testing of its prototype hydrogen tank onboard a liquid hydrogen (LH2) powered hybrid, LLNL's tank demonstrated a thermal endurance of six days and the potential for as much as 15 days, helping resolve a key challenge facing LH2 automobiles.........

Posted by: Sarah      Read more         Source

Older Blog Entries   1   2   3   4   5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52   53   54   55   56   57   58  
 

      Net World Directory: Navigation