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: Technology blog
light.jpg
 

Technology Blog From Networlddirectory


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


July 20, 2011, 10:29 PM CT

"Junk" Energy Into Useful Power

Research by physicist Surajit Sen has proven that crafting designer particles would enable scientists to control how energy travels through a granular system.
A University at Buffalo-led research team has developed a mathematical framework that could one day form the basis of technologies that turn road vibrations, airport runway noise and other "junk" energy into useful power.

The concept all begins with a granular system comprising a chain of equal-sized particles -- spheres, for instance -- that touch one another.

In a paper in Physical Review E this June, UB theoretical physicist Surajit Sen and his colleagues describe how altering the shape of grain-to-grain contact areas between the particles dramatically changes how energy propagates through the system.

Under "normal" circumstances, when the particles are perfect spheres, exerting force on the first sphere in the chain causes energy to travel through the spheres as a compact bundle of energy between 3 to 5 particle diameters wide, at a rate set by Hertz's Law.

But Sen and his collaborators have discovered that by altering the shape of the surface area of each particle where it presses against the next, it is possible to change how the energy moves. While this finding is yet to be demonstrated experimentally, Sen said that "mathematically, it's correct. We have proven it".

"What this work means is that by tweaking force propagation from one grain to another, we can potentially channel energy in controllable ways, which includes slowing down how energy moves, varying the space across which it moves and potentially even holding some of it down," said Sen, a professor of physics whose partners on the project included former graduate student Diankang Sun, now of New Mexico Resonance in Albuquerque, and Chiara Daraio, a professor at the California Institute of Technology.........

Posted by: Kevin      Read more         Source


March 28, 2011, 7:28 AM CT

First practical 'artificial leaf'

First practical 'artificial leaf'
esearchers today claimed one of the milestones in the drive for sustainable energy � development of the first practical artificial leaf. Speaking here at the 241st National Meeting of the American Chemical Society, they described an advanced solar cell the size of a poker card that mimics the process, called photosynthesis, that green plants use to convert sunlight and water into energy.

"A practical artificial leaf has been one of the Holy Grails of science for decades," said Daniel Nocera, Ph.D., who led the research team. "We believe we have done it. The artificial leaf shows particular promise as an inexpensive source of electricity for homes of the poor in developing countries. Our goal is to make each home its own power station," he said. "One can envision villages in India and Africa not long from now purchasing an affordable basic power system based on this technology".

The device bears no resemblance to Mother Nature's counterparts on oaks, maples and other green plants, which researchers have used as the model for their efforts to develop this new genre of solar cells. About the shape of a poker card but thinner, the device is fashioned from silicon, electronics and catalysts, substances that accelerate chemical reactions that otherwise would not occur, or would run slowly. Placed in a single gallon of water in a bright sunlight, the device could produce enough electricity to supply a house in a developing country with electricity for a day, Nocera said. It does so by splitting water into its two components, hydrogen and oxygen.........

Posted by: Kevin      Read more         Source


March 25, 2011, 7:33 AM CT

A New Phase of Matter

A New Phase of Matter
An unprecedented three-pronged study has found that one type of high-temperature superconductor may exhibit a new phase of matter. As in all superconductors, electrons pair off (bottom) to conduct electricity with no resistance when the material is cooled below a certain temperature. But in this particular copper-based superconductor, many of the electrons in the material don't pair off; instead they form a distinct, elusive order (orange plumes) that had not been seen before. (Illustration by Greg Stewart, SLAC.)

Researchers have found the strongest evidence yet that a puzzling gap in the electronic structures of some high-temperature superconductors could indicate a new phase of matter. Understanding this "pseudogap" has been a 20-year quest for scientists who are trying to control and improve these breakthrough materials, with the ultimate goal of finding superconductors that operate at room temperature.

"Our findings point to management and control of this other phase as the correct path toward optimizing these novel superconductors for energy applications, as well as searching for new superconductors," said Zhi-Xun Shen of the Stanford Institute for Materials and Energy Science (SIMES), a joint institute of the Department of Energy's SLAC National Accelerator Laboratory and Stanford University. Shen led the team of scientists that made the discovery; their findings are reported in the March 25 issue of Science.

Superconductors are materials that conduct electricity with 100 percent efficiency, losing nothing to resistance. Currently used in medical imaging, highly efficient electrical generators and maglev trains, they have the potential to become a truly transformative technology; energy applications would be just one beneficiary. This promise is hampered by one thing, though: they work only at extremely low temperatures. Eventhough research over the past 25 years has developed "high-temperature superconductors" that work at warmer temperatures, even the warmest of them-the cuprates-must be chilled half-way to absolute zero before they will superconduct.........

Posted by: Kevin      Read more         Source


March 15, 2011, 10:12 PM CT

Large Hadron Collider could be world's first time machine

Large Hadron Collider could be world's first time machine
An illustration of the Large Hadron Collider, the world's most powerful particle accelerator, located in Switzerland (CERN)
If the latest theory of Tom Weiler and Chui Man Ho is right, the Large Hadron Collider - the world's largest atom smasher that started regular operation last year - could be the first machine capable of causing matter to travel backwards in time.

"Our theory is a long shot," admitted Weiler, who is a physics professor at Vanderbilt University, "but it doesn't violate any laws of physics or experimental constraints".

A main goals of the collider is to find the elusive Higgs boson: the particle that physicists invoke to explain why particles like protons, neutrons and electrons have mass. If the collider succeeds in producing the Higgs boson, some researchers predict that it will create a second particle, called the Higgs singlet, at the same time.

As per Weiler and Ho's theory, these singlets should have the ability to jump into an extra, fifth dimension where they can move either forward or backward in time and reappear in the future or past.

"One of the attractive things about this approach to time travel is that it avoids all the big paradoxes," Weiler said. "Because time travel is limited to these special particles, it is not possible for a man to travel back in time and murder one of his parents before he himself is born, for example. However, if researchers could control the production of Higgs singlets, they might be able to send messages to the past or future".........

Posted by: Kevin      Read more         Source


March 13, 2011, 11:59 AM CT

New measurement technology

New measurement technology
Confocal micrograph of an actin-filamin network. Credit: Kurt Schmoller, Technische Universtaet Muenchen (Technical University of Munich)
The development of a new measurement technology under a research project funded by the Air Force Office of Scientific Research and the National Science Foundation is probing the structure of composite and biological materials.

"Our results have provided some of the first microscopic insights into a sixty year old puzzle about the way polymeric networks react to repeated shear strains," said Dr. Daniel Blair, Assistant Professor, and principal investigator of the Soft Matter Group in the Department of Physics at Georgetown University.

Blair, Professor Andreas Bausch and other scientists at Technische Universtaet Muenchen (Technical University of Munich) used the muscle filament known as actin to construct a unique polymer network. In their quest to understand more about bio-polymers, they developed the rheometer and confocal microscope system (measures the mechanical properties of materials), which provide a unique and unprecedented level of precision and sensitivity for investigating polymeric systems which were previously too small to visualize during mechanical stress experiments. The rheometer and confocal microscopes clearly visualized the fluorescently labeled actin network and they filmed the polymer filaments'movement in 3-D when mechanical stress was applied.........

Posted by: Kevin      Read more         Source


March 10, 2011, 7:55 AM CT

Black Holes: A Model for Superconductors?

Black Holes: A Model for Superconductors?
(l to r) Mohammad Edalati, Rob Leigh, and Philip Phillips. Not shown is co-author Ka Wai Lo.
Black holes are some of the heaviest objects in the universe. Electrons are some of the lightest. Now physicists Robert G. Leigh and Philip Phillips along with postdoctoral fellow Mohammad Edalati and graduate student Ka Wai Lo of the University of Illinois have shown how charged black holes can be used to model the behavior of interacting electrons in unconventional superconductors.

Unlike the old superconductors, which were all metals, the new superconductors start off their lives as insulators. In the insulating state of the copper-oxide materials, there are plenty of places for the electrons to hop but nonetheless-no current flows. Such a state of matter, known as a Mott insulator after the pioneering work of Sir Neville Mott, arises from the strong repulsions between the electrons. Eventhough this much is agreed upon, much of the physics of Mott insulators remains unsolved, because there is no exact solution to the Mott problem that is directly applicable to the copper-oxide materials.

Enter string theory-an evolving theoretical effort that seeks to describe the known fundamental forces of nature, including gravity, and their interactions with matter in a single, mathematically complete system.

In string theory, some strongly interacting quantum mechanical systems can be studied by replacing them with classical gravity in a space-time in one higher dimension, a relationship that was first conjectured by string theorist Juan Maldacena some fourteen years ago. The conjecture was made possible by thinking about D-branes, important objects in string theory, in two different but equivalent ways. Physical features of the quantum systems, such as temperature, charge density, etc., become properties of black holes in the classical gravity theory.........

Posted by: Kevin      Read more         Source


March 7, 2011, 6:55 AM CT

An 'eye' on nanoparticles

An 'eye' on nanoparticles
This is an optical microscope image of the microfluidic channel (light pattern) and sensing electrode (gold) of the analyzer. Nanoparticles are suspended in a fluid flow through the channel, and are detected individually as they pass through the sensing volume.

Credit: J.L. Fraikin and A.N. Cleland, UCSB

Precision measurement in the world of nanoparticles has now become a possibility, thanks to researchers at UC Santa Barbara.

The UCSB research team has developed a new instrument capable of detecting individual nanoparticles with diameters as small as a few tens of nanometers. The study will be published on line this week by Nature Nanotechnology, and appear in the April print issue of the journal.

"This device opens up a wide range of potential applications in nanoparticle analysis," said Jean-Luc Fraikin, the main author on the study. "Applications in water analysis, pharmaceutical development, and other biomedical areas are likely to be developed using this new technology." The instrument was developed in the lab of Andrew Cleland, professor of physics at UCSB, in collaboration with the group of Erkki Ruoslahti, Distinguished Professor, Sanford-Burnham Medical Research Institute at UCSB.

Fraikin is presently a postdoctoral associate in the Marth Lab at the Sanford-Burnham Medical Research Institute's Center for Nanomedicine, and in the Soh Lab in the Department of Mechanical Engineering at UC Santa Barbara.

The device detects the tiny particles, suspended in fluid, as they flow one by one through the instrument at rates estimated to be as high as half a million particles per second. Fraikin compares the device to a nanoscale turnstile, which can count �� and measure �� particles as they pass individually through the electronic "eye" of the instrument.........

Posted by: Kevin      Read more         Source


Mon, 17 Jan 2011 00:39:52 GMT

keeping things fresh and real in the dark box

keeping things fresh and real in the dark box
This Fridge Ionizer & Ozonator hums away quietly in your refrigerator killing all those nasty little bugs which degrade your foodstuffs. The result should be longer lasting produce and a happier, healthier family. Right? It’s battery powered and small enough to sit on a door shelf doing its duty. You’ll need to buy four for $49.15 to get them shipped, so gather up some friends.

 This unit quietly generates ions and ozone to counteract mold, mildew and bacterial growth for better air quality inside your refrigerator. The result is less odors and improved food quality. In addition, your fruits, vegetables and leftovers stay fresher and last longer. Compact and attractive, it has a built-in microprocessor to intelligently control the operation cycle in one easy touch.

Tags: gadget, fridge+ionizer+&+ozonator, health, kitchen Share and Enjoy:

Posted by: Redferret      Read more     Source


January 11, 2011, 7:03 AM CT

New Glass Tops Steel in Strength and Toughness

New Glass Tops Steel in Strength and Toughness
Micrograph of deformed notch in palladium-based metallic glass shows extensive plastic shielding of an initially sharp crack. Inset is a magnified view of a shear offset (arrow) developed during plastic sliding before the crack opened. (Image courtesy of Ritchie and Demetriou)
Glass stronger and tougher than steel? A new type of damage-tolerant metallic glass, demonstrating a strength and toughness beyond that of any known material, has been developed and tested by a collaboration of scientists with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab)and the California Institute of Technology. What's more, even better versions of this new glass appears to be on the way.

"These results mark the first use of a new strategy for metallic glass fabrication and we believe we can use it to make glass that will be even stronger and more tough," says Robert Ritchie, a materials scientist who led the Berkeley contribution to the research.

The new metallic glass is a microalloy featuring palladium, a metal with a high "bulk-to-shear" stiffness ratio that counteracts the intrinsic brittleness of glassy materials.

"Because of the high bulk-to-shear modulus ratio of palladium-containing material, the energy needed to form shear bands is much lower than the energy mandatory to turn these shear bands into cracks," Ritchie says. "The result is that glass undergoes extensive plasticity in response to stress, allowing it to bend rather than crack".

Ritchie, who holds joint appointments with Berkeley Lab's Materials Sciences Division and the University of California (UC) Berkeley's Materials Science and Engineering Department, is one of the co-authors of a paper describing this research reported in the journal Nature Materials under the title "A Damage-Tolerant Glass".........

Posted by: Kevin      Read more         Source


January 7, 2011, 6:59 AM CT

Study finds energy limits global economic growth

Study finds energy limits global economic growth
A study that relates global energy use to economic growth, reported in the recent issue of BioScience, finds strong correlations between these two measures both among countries and within countries over time. The research leads the study's authors to infer that energy use limits economic activity directly. They conclude that an "enormous" increase in energy supply will be mandatory to meet the demands of projected world population growth and lift the developing world out of poverty without jeopardizing standards of living in most developed countries.

The study, which used a macroecological approach, was based on data from the International Energy Agency and the World Resources Institute. It was conducted by a team of ecologists led by James H. Brown of the University of New Mexico. The team found the same sort of relationship between energy consumption per person and gross domestic product per person as is found between metabolism and body weight in animals. Brown's group suggests the similarity is real: cities and countries, like animals, have metabolisms that must burn fuel to sustain themselves and grow. This analogy, together with the data and theory, persuades the BioScience authors that the linkage between energy use and economic activity is causal, eventhough other factors must also be in play to explain the variability in the data.........

Posted by: Kevin      Read more         Source


December 25, 2010, 10:35 AM CT

Nuclear magnetic moments

Nuclear magnetic moments
uclear magnetic moment provides a highly sensitive probe into the single-particle structure and serves as a stringent test of nuclear models. In recent decades, the facilities with radioactive ion beam models to study nuclear magnetic moments make it possible to measure the magnetic moments of neutron-rich and proton-rich nuclei with high precision. On the theoretical side, a number of nuclear structure models, including advanced shell models, and self-consistent mean-field theories, have succeeded analyzing a number of nuclear structure properties. However, the extension of these models to the study of nuclear magnetic moments is quite limited and unsatisfactory. The magnetic dipole moments of most atomic nuclei throughout the periodic table still remain unexplained and the under-lying physics mechanism is not fully understood.

In view of these facts, SCIENCE CHINA: Physics, Mechanics & Astronomy editorial board has invited many major theoretical nuclear physicists in the research field of nuclear magnetic moments and correlation topics to contribute to this special topic. However, due to the page limitation the discussion on the topic presents just a fraction of the progress in this field.

This special issue on "Nuclear magnetic moments and correlation topics" consists of ten selected papers, which review the progress not only on the theoretical description of nuclear magnetic moments, but also on the recent development of closely related subjects including nuclear pairing, quantum phase transitions as well as nuclear masses in microscopic models. This issue is also intended to identify common goals to deepen understanding of nuclear structure.........

Posted by: Kevin      Read more         Source


December 13, 2010, 7:40 AM CT

Directed self-assembly of vertical nanotubes

Directed self-assembly of vertical nanotubes
NJIT research professor Reggie Farrow is available today at the NJIT booth at the National Nanotechnology Innovation Summit at the Gaylord Center, Washington, D.C.

Credit: NJIT

"Directed Self-Assembly of Vertical Nanotubes for Biosensors, Logic, and Nano-Biofuel Cells," will be the focus of NJIT's exhibit today .

at the National Nanotechnology Innovation Summit 10 http://www.nsti.org/events/NNI/, at the Gaylord Center in Washington, DC. The event celebrates the 10th anniversary of the national nanotechnology initiative.

NJIT was the only university in New Jersey selected for this exposition featuring practical applications of nanoscience resulting from the last decade of federal funding under the National Nanotechnology Initiative (NNI).

On view are four nanotech projects, each one illustrating innovative and practical approaches to creating structured, functional devices at molecular scales. The projects are based upon the work of NJIT Research Professors Reggie Farrow and Zafar Iqbal http://chemistry.njit.edu/people/iqbal.php. The US Department of Defense provided support for the work.

Project titles are: Directed Self-Assembly of Vertical Single Wall Carbon Nanotubes; Nano-Bioprobe Array for Subcellular Electrophysiology; Nanoscalable Enzymatic Biofuel Cells; Carbon Nanotube 3D Integrated Circuits. To receive by email a copy of a technology brief detailing each project, contact Judith Sheft, associate vice president of technology development, sheft@njit.edu: 973-596-5825.........

Posted by: Kevin      Read more         Source


November 18, 2010, 7:31 AM CT

Antimatter atoms stored

Antimatter atoms stored
An artist's impression of an antihydrogen atom -- a negatively charged antiproton orbited by a positively charge anti-electron, or positron -- trapped by magnetic fields.

Credit: Graphic by Katie Bertsche

Atoms of antimatter have been trapped and stored for the first time by the ALPHA collaboration, an international team of researchers working at CERN, the European Organization for Nuclear Research near Geneva, Switzerland. Researchers from the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley have made key contributions to the ongoing international effort.

ALPHA stored atoms of antihydrogen, consisting of a single negatively charged antiproton orbited by a single positively charged anti-electron (positron). While the number of trapped anti-atoms is far too small to fuel the Starship Enterprise's matter-antimatter reactor, this advance brings closer the day when researchers will be able to make precision tests of the fundamental symmetries of nature. Measurements of anti-atoms may reveal how the physics of antimatter differs from that of the ordinary matter that dominates the world we know today.

Large quantities of antihydrogen atoms were first made at CERN eight years ago by two other teams. Eventhough they made antimatter they couldn't store it, because the anti-atoms touched the ordinary-matter walls of the experiments within millionths of a second after forming and were instantly annihilatedcompletely destroyed by conversion to energy and other particles.........

Posted by: Kevin      Read more         Source


November 18, 2010, 7:06 AM CT

Nanoscale probe reveals interactions

Nanoscale probe reveals interactions
Simultaneously acquired images and polarizability maps of four different families of molecules
As electronics become smaller and smaller the need to understand nanoscale phenomena becomes greater and greater. Because materials exhibit different properties at the nanoscale than they do at larger scales, new techniques are mandatory to understand and to exploit these new phenomena. A team of scientists led by Paul Weiss, UCLA's Fred Kavli Chair in NanoSystems Sciences, has developed a tool to study nanoscale interactions. Their device is a dual scanning tunneling and microwave-frequency probe that is capable of measuring the interactions between single molecules and the surfaces to which the molecules are attached.

"Our probe can generate data on the physical, chemical, and electronic interactions between single molecules and substrates, the contacts to which they are attached. Just as in semiconductor devices, contacts are critical here," remarked Weiss, who directs UCLA's California NanoSystems Institute and is also a distinguished professor of chemistry and biochemistry & materials science and engineering.

The team, which also includes theoretical chemist Mark Ratner from Northwestern University and synthetic chemist James Tour from Rice University, published their findings in the peer-evaluated journal ACS Nano.

For the past 50 years, the electronics industry has endeavored to keep up with Moore's Law, the prediction made by Gordon E. Moore in 1965 that the size of transistors in integrated circuits would halve approximately every two years. The pattern of consistent decrease in the size of electronics is approaching the point where transistors will have to be constructed at the nanoscale to keep pace. However, scientists have encountered obstacles in creating devices at the nanoscale because of the difficulty of observing phenomena at such minute sizes.........

Posted by: Kevin      Read more         Source


November 17, 2010, 7:59 AM CT

Linking geometric problems to physics

Linking geometric problems to physics
A Princeton scientist with an interdisciplinary bent has taken two well-known problems in mathematics and reformulated them as a physics question, offering new tools to solve challenges relevant to a host of subjects ranging from improving data compression to detecting gravitational waves.

Salvatore Torquato, a professor of chemistry, has shown that two abstract puzzles in geometry -- known as the "covering" and "quantizer" problems -- can be recast as "ground state" problems in physics. Ground state problems relate to the study of molecule systems at their lowest levels of energy and have numerous applications across scientific disciplines. Torquato's conclusions are reported in a paper that was published online Nov. 10 by Physical Review E.

"This paper describes what I believe to be a wonderful example of the deep interplay between geometry and physics," Torquato said. The problem of determining the ground states of special interacting particles, which is relevant to studies of conditions of materials approaching absolute zero, is directly applicable to these math questions, he explained.

"In other words," Torquato said, "what appear to be abstract mathematical problems can be correlation to the cooling of special liquids that undergo phase transitions to crystal states at a temperature of absolute zero. These reformulations are completely new to my knowledge".........

Posted by: Kevin      Read more         Source


November 11, 2010, 6:54 AM CT

Highly efficient, flexible nanogenerator technology

Highly efficient, flexible nanogenerator technology
Flexible thin film nanomaterials produce electricity.

Credit: KAIST

Can a heart implanted micro robot operate permanently? Can cell phones and tiny robots implanted in the heart operate permanently without having their batteries charged?

It might sound like science fiction, but these things seem to be possible in the near future.

The team of Prof. Keon Jae Lee (KAIST, Dept. of Materials Science and Engineering) and Prof. Zhong Lin Wang (Georgia Institute of Technology, Dept. of Materials Science and Engineering) has developed new forms of highly efficient, flexible nanogenerator technology using the freely bendable piezoelectric ceramic thin film nano-materials that can convert tiny movements of the human body (such as heart beats and blood flow) into electrical energy.

The piezoelectric effect refers to voltage generation when pressure or bending strength is applied to piezoelectric materials. The ceramics, containing a perovskite structure, have a high piezoelectric efficiency. Until now, it has been very difficult to use these ceramic materials to fabricate flexible electronic systems due to their brittle property.

The research team, however, has succeeded in developing a bio-eco-friendly ceramic thin film nanogenerator that is freely bendable without breakdown.

Nanogenerator technology, a power generating system without wires or batteries, combines nanotechnology with piezoelectrics that can be used not only in personal mobile electronics but also in bio-implantable sensors or as an energy source for micro robots. Energy sources in nature (wind, vibration, and sound) and biomechanical forces produced by the human body (heart beats, blood flow, and muscle contraction/relaxation) can infinitely produce nonpolluting energy.........

Posted by: Kevin      Read more         Source


November 8, 2010, 7:23 AM CT

Taming thermonuclear plasma with a snowflake

Taming thermonuclear plasma with a snowflake
Physicists working on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Laboratory are now one step closer to solving one of the grand challenges of magnetic fusion researchhow to reduce the effect that the hot plasma has on fusion machine walls (or how to tame the plasma-material interface). Some heat from the hot plasma core of a fusion energy device escapes the plasma and can interact with reactor vessel walls. This not only erodes the walls and other components, but also contaminates the plasmaall challenges for practical fusion. One method to protect machine walls involves divertors, chambers outside the plasma into which the plasma heat exhaust (and impurities) flow. A new divertor concept, called the "snowflake," has been shown to significantly reduce the interaction between hot plasma and the cold walls surrounding it.

Strong magnetic fields shape the hot plasma in the form of a donut in a magnetic fusion plasma reactor called a tokamak. As confined plasma particles move along magnetic field lines inside the tokamak, some particles and heat escape because of instabilities in the plasma. Surrounding the hot plasma is a colder plasma layer, the scrape-off layer, which forms the plasma-material interface. In this layer, escaped particles and heat flow along an "open" magnetic field line to a separate part of the vessel and enter a "divertor chamber." If the.........

Posted by: Kevin      Read more         Source


November 8, 2010, 7:21 AM CT

Vacuum arcs spark new interest

Vacuum arcs spark new interest
Even in a vacuum, voltages can literally tear metal apart. Current research is using molecular dynamics to show what happens at the atomic level when material is damaged by arcing in vacuum.

Credit: J. Norem, Z. Insepov, Th. Proslier, D. Huang, S. Mahalingam, and S. Veitzer

Whenever two pieces of metal at different voltages are brought near each other, as when an appliance is plugged into a live socket, there is a chance there will be an arc between them. Most of the arcs people see are a breakdown of the gas between the metal surfaces, but this type of breakdown can also occur in a vacuum. This vacuum breakdown, which until recently has not been well understood, has implications for applications from particle accelerators to fusion reactors.

As part of an effort to understand the maximum accelerating field in particle accelerators, researchers at Argonne National Laboratory have been modeling the processes involved in vacuum breakdown. Now, a new model of this phenomenon is beginning to reveal what is happening in these arcs, and researchers are studying many new phenomena linked to them.

In this new model, the breakdown arc is triggered by the electric field in the vacuum gap literally tearing the metal apart. (The same force that causes "static cling" can be very powerful for high electric fields, especially at tiny corners, and in cracks where the fields are intensified by the local geometry of the surface.) After the metal is torn apart, the fragments should become ionized and form microscopic plasmas that are very dense and cold (for a plasma). Because of the high densities in these plasmas, the surface fields inside the arc quickly become even stronger than they were at breakdown. The arc becomes very damaging to the metal surface over a comparatively large area, eventually leaving a pit that should be visible to the naked eye.........

Posted by: Kevin      Read more         Source


November 5, 2010, 8:01 AM CT

Pennycress as a New Source of Biofuel

Pennycress as a New Source of Biofuel
A common roadside plant could have the right stuff to become a new source of biofuel, as per U.S. Department of Agriculture (USDA) studies. Researchers with the Agricultural Research Service (ARS), USDA's principal intramural scientific research agency, have observed that field pennycress yields impressive quantities of seeds whose oil could be used in biodiesel production.

Field pennycress belongs to the Brassicaceae family, along with canola, camelina and mustard-other prolific producers of oil-rich seeds. The ARS studies help support USDA's efforts to develop new sources of bioenergy.

At the ARS National Center for Agricultural Utilization Research in Peoria, Ill., chemists Bryan Moser, Gerhard Knothe and Terry Isbell and plant physiologist Steven Vaughn formed a team to study field pennycress' potential.

The researchers obtained oil from wild field pennycress, pretreated it with acid, and used a type of alcohol called methanol to react with the field pennycress oil to produce both biodiesel and glycerol. After some additional refining, the finished biodiesel was tested to see if it met the biodiesel fuel standard established by the American Society for Testing and Materials. The results suggested that, with some work, the previously problematic pennycress could become a commercial commodity.........

Posted by: Kevin      Read more         Source


November 3, 2010, 7:55 AM CT

Long-range undersea robot goes the distance

Long-range undersea robot goes the distance
research. Today's AUVs fall into two groups: 1) propeller-driven vehicles that can travel fast and carry lots of instruments, but are limited to expeditions of only a few days; and 2) "gliders," which can stay at sea for weeks or even months at a time, but cannot travel very quickly. MBARI engineers recently demonstrated a new super-efficient AUV that combines the best of these two approaches. This new long-range AUV (LRAUV) can travel rapidly for hundreds of kilometers, "hover" in the water for weeks at a time, and carry a wide variety of instruments.

The new robot, called Tethys, spent most of October crisscrossing Monterey Bay as part of MBARI's CANON experiment. Oceanographers used Tethys to track patches of microscopic algae that were carried around the bay by currents. During this experiment, the robot showed that it could travel fast enough to buck the currents, but could also go into "hover mode" to drift with the currents when needed.

In "high-speed mode" the LRAUV can travel up to one meter per second (2.25 miles an hour) - about four times faster than most underwater gliders. However, it can also travel long distances at around half this speed.

After spending four years designing, building, and testing Tethys, MBARI engineers were happy to see it working out in the real ocean. In fact, the AUV performed even better than expected. The AUV completed a four-day science run with plenty of battery power remaining, using relatively low-power rechargeable batteries. Based on these promising initial results, the scientists hope that the little robot will eventually be able to travel from California to Hawaii using high-power disposable batteries.........

Posted by: Kevin      Read more         Source


November 3, 2010, 7:47 AM CT

Algae for biofuels

Algae for biofuels
Algae is considered a prime candidate to serve as feedstock for biofuels because of its high energy content and yield, rapid growth and ability to thrive in seawater or wastewater. Oil from algae can be refined into gasoline, biodiesel or jet fuel.

Credit: Photo courtesy of Sandia National Laboratories

A new report from the Energy Biosciences Institute (EBI) in Berkeley projects that development of cost-competitive algae biofuel production will require much more long-term research, development and demonstration. In the meantime, several non-fuel applications of algae could serve to advance the nascent industry.

"Even with relatively favorable and forward-looking process assumptions (from cultivation to harvesting to processing), algae oil production with microalgae cultures will be expensive and, at least in the near-to-mid-term, will require additional income streams to be economically viable," write authors Nigel Quinn and Tryg Lundquist of Lawrence Berkeley National Laboratory (Berkeley Lab), which is a partner in the BP-funded institute.

Their conclusions stem from a detailed techno-economic analysis of algal biofuels production. The project is one of the over 70 studies on bioenergy now being pursued by the EBI and its researchers at the University of California at Berkeley, the University of Illinois in Urbana-Champaign, and Berkeley Lab.

The algae biofuels industry is still in its early gestation stage, the new report notes. Eventhough well over 100 companies in the U.S. and abroad are now working to produce algal biomass and oil for transportation fuels, most are small and none has yet operated a pilot plant with multiple acres of algae production systems. However, several companies recently initiated such scale-up projects, including several major oil companies such as ExxonMobil (which a year ago announced a $600 million commitment to algae biofuels technology), Shell (with a joint venture project, "Cellana," in Hawaii), and Eni (the Italian oil company, with a pre-pilot plant in Sicily).........

Posted by: Kevin      Read more         Source


October 26, 2010, 8:09 AM CT

Stable way to store the sun's heat

Stable way to store the sun's heat
Scientists at MIT have revealed exactly how a molecule called fulvalene diruthenium, which was discovered in 1996, works to store and release heat on demand. This understanding, reported in a paper published on Oct. 20 in the journal Angewandte Chemie, should make it possible to find similar chemicals based on more abundant, less expensive materials than ruthenium, and this could form the basis of a rechargeable battery to store heat rather than electricity.

The molecule undergoes a structural transformation when it absorbs sunlight, putting it into a higher-energy state where it can remain stable indefinitely. Then, triggered by a small addition of heat or a catalyst, it snaps back to its original shape, releasing heat in the process. But the team observed that the process is a bit more complicated than that.

"It turns out there's an intermediate step that plays a major role," said Jeffrey Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering in the Department of Materials Science and Engineering. In this intermediate step, the molecule forms a semi-stable configuration partway between the two previously known states. "That was unexpected," he said. The two-step process helps explain why the molecule is so stable, why the process is easily reversible and also why substituting other elements for ruthenium has not worked so far.........

Posted by: Kevin      Read more         Source


October 11, 2010, 7:55 AM CT

Depressurization tests to verify flight design

Depressurization tests to verify flight design
Northrop Grumman lead venting analyst Dan McGregor inspects a sunshield test article for the sunshield section on top of the spacecraft around the tower that supports the telescope.

Credit: Northrop Grumman Aerospace Systems
NASA's James Webb Space Telescope continues to make significant progress, successfully completing a series of sunshield vent tests that validate the telescope's sunshield design.

"While adequate venting is a design consideration for all spaceflight hardware, this was a especially unique challenge for the sunshield given the large volume of trapped air in the membrane system at launch," said Keith Parrish, Webb telescope sunshield manager at NASA's Goddard Space Flight Center in Greenbelt, Md. "From the beginning of its development venting features have been a critical part of the overall sunshield design. Since we cannot vent test the actual flight article these test have shown the design works and the sunshield will vent safely on its way to orbit".

The sunshield on the Webb telescope will block the heat of the Sun and Earth from reaching the cold section of the Observatory. That's a critical function because the telescope and instruments must be cooled below 50 Kelvin (~-369.7 Fahrenheit) to allow them to see faint infrared emissions from astronomical objects. The sunshield consists of five layers of Kapton E with aluminum and doped-silicon coatings to reflect the sun's heat back into space.

Using flight-like sunshield membranes, the tests are designed to mimic the rapid change in air pressure the folded sunshield will experience the first minutes of launch. Several different folding configurations each underwent a series of 90-second depressurization tests and proved that the stowed sunshield will retain its shape during launch and allow trapped air to escape safely, both critical to sunshield deployment and performance.........

Posted by: Kevin      Read more         Source


October 8, 2010, 7:57 AM CT

Simplifying biodiesel conversion

Simplifying biodiesel conversion
Waste not, want not
Aaron Socha, left, and Jason Sello devised a way to convert waste vegetable oil to biodiesel in a single reaction vessel, using environmentally friendly catalysts.
Credit: Mike Cohea/Brown University
As the United States seeks to lessen its reliance on foreign oil, biodiesel is expected to play a role. As per the National Renewable Energy Laboratory, a branch of the Department of Energy, biodiesel "represents a significant energy resource and could someday supply 3 percent to 5 percent of the distillate fuel market".

One major obstacle to achieving that goal is figuring how to efficiently convert the abundant stocks of waste vegetable oil (oil used after cooking French fries, for example) into biodiesel fuel. Current techniques take time, are costly and are inefficient. Worse, the conversion requires the toxic chemicals sulfuric acid and either potassium hydroxide or sodium hydroxide.

That's where Brown University chemist Jason Sello and postdoctoral researcher Aaron Socha come in. They write in the journal Organic & Biomolecular Chemistry that they were able to convert waste vegetable oil to biodiesel in a single reaction vessel using environmentally friendly catalysts. Their process is also six times faster than current methods for converting waste vegetable oil to biodiesel, so it consumes less energy.

"We wanted to develop an environmentally non-malignant and technically simple way to convert waste vegetable oil into biodiesel," said Sello, assistant professor of chemistry. "The production of energy at the expense of the environment is untenable and should be avoided at all costs".........

Posted by: Kevin      Read more         Source


September 25, 2010, 7:57 AM CT

Biometric ID technologies 'nherently fallible

Biometric ID technologies 'nherently fallible
Biometric systems -- designed to automatically recognize individuals based on biological and behavioral traits such as fingerprints, palm prints, or voice or face recognition -- are "inherently fallible," says a new report by the National Research Council, and no single trait has been identified that is stable and distinctive across all groups. To strengthen the science and improve system effectiveness, additional research is needed at virtually all levels of design and operation.

"For nearly 50 years, the promise of biometrics has outpaced the application of the technology," said Joseph N. Pato, chair of the committee that wrote the report and distinguished technologist at Hewlett-Packard's HP Laboratories, Palo Alto, Calif. "While some biometric systems can be effective for specific tasks, they are not nearly as infallible as their depiction in popular culture might suggest. Bolstering the science is essential to gain a complete understanding of the strengths and limitations of these systems".

Biometric systems are increasingly used to regulate access to facilities, information, and other rights or benefits, but questions persist about their effectiveness as security or surveillance mechanisms. The systems provide "probabilistic results," meaning that confidence in results must be tempered by an understanding of the inherent uncertainty in any given system, the report says. It notes that when the likelihood of an imposter is rare, even systems with very accurate sensors and matching capabilities can have a high false-alarm rate. This could become costly or even dangerous in systems designed to provide heightened security; for example, operators could become lax about dealing with potential threats.........

Posted by: Kevin      Read more         Source


September 22, 2010, 7:30 AM CT

Lasers to Cool and Control Molecules

Lasers to Cool and Control Molecules
Ever since audiences heard Goldfinger utter the famous line, "No, Mr. Bond; I expect you to die," as a laser beam inched its way toward James Bond and threatened to cut him in half, lasers have been thought of as white-hot beams of intensely focused energy capable of burning through anything in their path.

Now a team of Yale physicists has used lasers for a completely different purpose, employing them to cool molecules down to temperatures near what's known as absolute zero, about -460 degrees Fahrenheit. Their new method for laser cooling, described in the online edition of the journal Nature, is a significant step toward the ultimate goal of using individual molecules as information bits in quantum computing.

Currently, researchers use either individual atoms or "artificial atoms" as qubits, or quantum bits, in their efforts to develop quantum processors. But individual atoms don't communicate as strongly with one another as is needed for qubits. Conversely, artificial atoms-which are actually circuit-like devices made up of billions of atoms that are designed to behave like a single atom-communicate strongly with one another, but are so large they tend to pick up interference from the outside world. Molecules, however, could provide an ideal middle ground.........

Posted by: Kevin      Read more         Source


September 11, 2010, 9:03 AM CT

A layer of graphene in action

A layer of graphene in action
A layer of graphene is shown with a tiny nanopore drilled into its surface. Researchers at Harvard and MIT demonstrated that the membrane holds potential for speeding up DNA sequencing due to its extreme thinness.

Credit: Lab of Jene Golovchenko, Harvard University.

In a paper published as the cover story of the September 9, 2010 Nature, scientists from Harvard University and MIT have demonstrated that graphene, a surprisingly robust planar sheet of carbon just one-atom thick, can act as an artificial membrane separating two liquid reservoirs.

By drilling a tiny pore just a few-nanometers in diameter, called a nanopore, in the graphene membrane, they were able to measure exchange of ions through the pore and demonstrated that a long DNA molecule can be pulled through the graphene nanopore just as a thread is pulled through the eye of a needle.

"By measuring the flow of ions passing through a nanopore drilled in graphene we have demonstrated that the thickness of graphene immersed in liquid is less then 1 nm thick, or a number of times thinner than the very thin membrane which separates a single animal or human cell from its surrounding environment," says main author Slaven Garaj, a Research Associate in the Department of Physics at Harvard. "This makes graphene the thinnest membrane able to separate two liquid compartments from each other. The thickness of the membrane was determined by its interaction with water molecules and ions".

Graphene, the strongest material known, has other advantages. Most importantly, it is electrically conductive.........

Posted by: Kevin      Read more         Source


September 8, 2010, 7:10 AM CT

Computer-based video analysis

Computer-based video analysis
For decades, carefully logging data about how mice go through the motions of their daily routines has been a tedious staple of behavioral and neuroscience research:
  • Hour 2, minute 27: mouse 4 is sleeping;
  • Hour 3, minute 12: mouse 7 is eating;
.

and so on. It's a task most people would happily cede to automation. Now, says Thomas Serre, assistant professor of cognitive, linguistic and psychological sciences at Brown University, that's finally possible.

In a paper to be published online Sept. 7, 2010, in the journal Nature Communications, Serre and a team of colleagues at the Massachusetts Institute of Technology and California Institute of Technology describe a new computer system that is as accurate as people in identifying mouse behaviors in videos. What's more, the team is making the fully customizable open-source software available for free. Given standard camcorder footage of a mouse, the software will automatically identify a mouse's behavior frame by frame.

"We measured the agreement [on mouse behaviors] between any two human observers and it was more than 70 percent," said Serre, who joined the Brown faculty in January 2010 after conducting his doctoral and postdoctoral studies, including the work described in the paper, at MIT. "The system agreed with humans at the same level. There was no significant difference between the annotations provided by our system and any two human observers".........

Posted by: Kevin      Read more         Source


August 26, 2010, 7:21 AM CT

Trouble with Sputter?

Trouble with Sputter?
Graduate student Lan Zhou and her advisor Randy Headrick made a fundamental discovery in physics that may improve computer chips, solar panels, x-ray lenses, and even your next pair of mirrored sunglasses. (Photo: Sally McCay)
When you tear open a bag of potato chips or pop in a DVD, you're probably putting your hand on sputter deposition. No, don't run for the soap.

Sputter deposition is an industrial process used since the 1970s to spray -- sputter, that is -- thin films onto various backings, like the metallic coating on potato chip bags, the reflective surface on DVDs, or the electronics on computer chips.

Mostly, the process works very well. In a vacuum chamber filled with an inert gas, like argon, high voltage is applied to a magnet. This energizes the argon, which, in turn, bumps particles of, say, tungsten metal from a source near the magnet out into the cloud of gas. Some of these extremely hot, charged tungsten particles zip at high speed through the argon and deposit onto the target, forming a thin film.

But sometimes the coatings peel off or the product bends in on itself and cracks, as if the film was stretched tight before it was applied to the surface. Other times, the films are just too rough. For decades, researchers have been baffled -- and manufacturers frustrated -- about why these problems happen.

Particle pile-up

Now scientists at the University of Vermont and the Argonne National Laboratory near Chicago have an explanation: "it's nanoparticles," says Randy Headrick, professor of physics at UVM, "sticking and pulling together".........

Posted by: Kevin      Read more         Source


August 25, 2010, 7:14 AM CT

LEDs promise brighter future

LEDs promise brighter future
Solid-state lighting pioneers long have held that replacing the inefficient Edison light bulb with more efficient solid-state light-emitting devices (LEDs) would lower electrical usage worldwide, not only "greenly" decreasing the need for new power plants but even permitting some to be decommissioned.

But, in a paper published Thursday in the Journal of Physics D, leading LED scientists from Sandia National Laboratories argue for a shift in that view.

"Presented with the availability of cheaper light, humans may use more of it, as has happened over recent centuries with remarkable consistency following other lighting innovations," said Sandia lead researcher Jeff Tsao. "That is, rather than functioning as an instrument of decreased energy use, LEDs appears to be instead the next step in increasing human productivity and quality of life".

The assumption that energy production for lighting will decline as the efficiency of lighting increases is contraindicated by data starting with the year A.D. 1700 that shows light use has remained a constant fraction of per capita gross domestic product as humanity moved from candle to oil to gas to electrical lighting. Thus the societal response to more efficient light production has been a preference to enjoy more light, rather than saving money and energy by keeping the amount of light produced a constant.........

Posted by: Kevin      Read more         Source


August 24, 2010, 5:44 PM CT

Atmospheric pressure plasma jet

Atmospheric pressure plasma jet
Photographs of atmospheric pressure plasma jet and Schlieren photograph of helium gas flow showing obvious interplay of the jet with the carrying gas flow. Numbers at left specify the gas flow rate in liter/hour. Applied voltage: 8 kV
Because they are portable and easy to operate at ambient temperatures, cold atmospheric pressure plasma jets (APPJs) should find innovative applications in biomedicine, materials science and fabrication industries. Research published in the Journal of Applied Physics investigates an APPJ that extends from the ground electrode of a circuit.

The scientists studied the mechanism of the jet, which differs from conventional APPJ applications that form at the active electrode.

"The ground electrode jets originate from a charge overflow and are powered by the dielectric barrier discharge between the electrodes," say authors Nan Jiang and Zexian Cao of the Beijing National Laboratory for Condensed Matters in China. "They are therefore isolated from electrical breakdown when the jet approaches an object."

This separation between the jet and active electrode, along with the ability to form a jet at lower voltages than conventional APPJs increases operator safety and opens up biomedical applications that would be dangerous otherwise.

By using narrow, transparent ground electrodes, the scientists observed that the overflow jet begins to develop at the inner edge of the ground electrode, and propagates forward in the dielectric via surface microdischarge which, to the surprise of the authors, causes backstreaming of charges. The output characteristics of the jet can be tuned by adjusting the conditions of dielectric barrier discharge between the electrodes and by varying the width of the ground electrode.........

Posted by: Kevin      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   59   60   61   62   63   64   65   66   67   68   69   70   71   72   73   74  
 

      Net World Directory: Navigation