August 26, 2007, 10:52 AM CT

Solar Cells May Bring Cheaper Green Power

Researchers are researching new ways of harnessing the sun's rays which could eventually make it cheaper for people to use solar energy to power their homes.

The experts at Durham University are in the process of developing light-absorbing materials for use in the production of thin-layer solar photovoltaic (PV) cells which are used to convert light energy into electricity.

The four-year project involves experiments on a range of different materials that would be less expensive and more sustainable to use in the manufacturing of solar panels.

Thicker silicon-based cells and compounds containing indium, a rare and expensive metal, are more usually used to make solar panels today.

The research, funded by the Engineering and Physical Sciences Research Council (EPSRC) SUPERGEN Initiative, focuses on developing thin-layer PV cells using materials such as copper indium diselenide and cadmium telluride.

Right now the project is entering a new phase for the development of cheaper and more sustainable variants of these materials.

The Durham team is also working on manipulating the growth of the materials so they form a continuous structure which is essential for conducting the energy trapped by solar panels before it is turned into usable electricity. This will help improve the efficiency of the thin-layer PV cells......... Posted by: Kevin      Read more         Source

August 26, 2007, 10:49 AM CT

New Finding Bubbles To Surface

Chemical engineers have discovered a fundamental flaw in the conventional view of how liquids form bubbles that grow and turn into vapors, which takes place in everything from industrial processes to fizzing champagne.

The findings cast into doubt some aspects of a theory dating back to the 1920s that attempts to describe the underlying molecular mechanism behind a phenomenon called "homogeneous nucleation," said David S. Corti, an associate professor of chemical engineering at Purdue University.

The research could lead to a more precise understanding of the "phase transition" that takes place when bubbles form, grow and then become a vapor, which could, in turn, have implications for industry and research, Corti said.

In the conventional view, a liquid boiling and turning into a vapor takes place in a systematic process known as "nucleation and growth." The liquid first forms tiny "nuclei," or microscopic bubbles, that eventually grow as they pick up particles like a snowball gaining size as it rolls down a hillside. This conventional view is described by "classical nucleation theory," which was originally proposed in the 1920s.

"Our findings indicate that this is not what's going on," Corti said. "The bubble grows via a mechanism very different from classical nucleation theory"......... Posted by: Kevin      Read more         Source

August 25, 2007, 7:18 AM CT

Highly sensitive weather radar

TU Delft has taken a new weather radar system into use, the 'Drizzle Radar', which can observe even the lightest of drizzles. This is an enormous gain for climate scientists and is attracting international attention. The radar was successfully installed on the 213 metre-high Royal Netherlands Meteorological Institute (KNMI) measurement tower in Cabauw, near Lopik, on Thursday, August 23. From this spot the highly sensitive radar, together with the other advanced instruments of the CESAR observatory (Cabauw Experimental Site for Atmospheric Research), is to provide a complete picture of the interaction between dust, clouds, rain and radiation. The latter is still one of the least understood factors in climate models.

Clouds and the climate

Clouds are of great importance for the greenhouse effect. On the one hand, clouds wrap a blanket round the Earth which retains heat, but they also cool the planet through the reflection of sunlight. Clouds can therefore compensate for some of the global warming, but the question is how much, and how precisely does it work. Dust particles play a crucial role in the formation of clouds and precipitation. They act as condensation nuclei, around which small droplets form. The more dust particles, the more dense the clouds, the more solar radiation is reflected and the cooler the Earth stays......... Posted by: Kevin      Read more         Source

August 23, 2007, 10:28 PM CT

Ground-breaking antilandmine radar

Scientists in The Netherlands are in the process of developing a radar system that might one day see through solid earth and could be used to clear conflict zones of landmines, safely and at low cost. Writing in Inderscience's Journal of Design Research, the team explains how the new technology, with further industrial development, could eventually make vast tracts of land around the globe safe once more.

Landmines were first used widely during World War II and continue to represent a significant threat to life and limb in areas afflicted by war. Originally, landmines were used to protect strategic areas such as borders, camps or important bridges and to restrict the movement of enemy forces. The use of landmines has spread to countless national conflicts and they are now usually used by terrorist and other organizations against civilians and rivals. This has led to a major proliferation of landmines in a number of areas beyond conventional military conflict zones.

In the absence of records, the low cost of landmines and the vast areas that have been polluted with them due to aerial distribution, clearing landmines has become and increasingly frustrating and hazardous task.

A single landmine might cost $1, but once in the ground locating it and making it safe can cost up to $1000. As per P. van Genderen and A.G. Yarovoy in the Faculty of Electrical Engineering at Delft University of Technology, this cost is prohibitive in most areas affected by landmine use and so a cheaper solution is needed. The scientists also point out that a detection system that does not distinguish between landmines and other buried objects is not viable......... Posted by: Kevin      Read more         Source

August 21, 2007, 6:20 PM CT

molecules in living cells

Clemson University chemists have developed a method to dramatically improve the longevity of fluorescent nanoparticles that may someday help scientists track the motion of a single molecule as it travels through a living cell.

The chemists are exploiting a process called resonance energy transfer, which occurs when fluorescent dye molecules are added to the nanoparticles. Their findings will be reported at the 234th annual national American Chemical Society meeting Aug.19-24 in Boston.

If researchers could track the motion of a single molecule within a living cell it could reveal a world of information. Among other things, researchers could determine how viruses invade a cell or how proteins operate in the body. Such technology also could help doctors pinpoint the exact location of cancer cells in order to better focus therapy and minimize damage to healthy tissue. Outside the body, the technology could help speed up detection of such toxins as anthrax.

The key to developing single-molecule tracking technology may be the development of better fluorescent nanoparticles.

Fluorescent nanoparticles are thousands of times smaller than the width of a human hair and are similar in size to protein molecules, to which they can be attached. When illuminated by a laser beam inside a light microscope equipped with a sensitive digital camera, the nanoparticle attached to a protein will light up, allowing researchers to get a precise fix on the position of the protein and monitor its motion inside a cell......... Posted by: Kevin      Read more         Source

August 21, 2007, 5:21 PM CT

e-Science points to pollution solutions

Results from a UK e-Science project are helping to solve two pressing environmental problems. One finding could help to avoid arsenic contamination of drinking water extracted from man-made wells. Another could lead to improved methods of removing the now-banned industrial chemical, dioxin, from soil. The results were obtained using e-Science techniques and grid computing to simulate all the possible interactions between these contaminants and rock or soil.

Arsenic often appears in minerals rich in iron and sulphur, such as pyrite (fools gold). Researchers working as part of eMinerals, a major project funded under the Natural Environment Research Councils e-Science programme, have found out precisely how arsenic is taken up and held in the pyrite structure and the factors likely to lead to its release. We now know that arsenic replaces the sulphur in pyrite rather than the iron, and that pyrite is likely to dissolve more easily when arsenic is present, says Dr Kate Wright, who worked on the project. Further work could identify ways of stabilising arsenic-containing iron sulphide rock by introducing additives that slow the rate at which it dissolves.

The eMinerals project observed that a dioxin molecule will bind more strongly to clay surfaces the more chlorine atoms it contains, irrespective of the position of the chlorine atoms in the dioxin molecule. It also observed that binding is stronger the greater the electrical charge on the surface. However, water competes with dioxin to bind to surfaces and, in practice, a dioxin molecules ability to bind to a surface is a balance between the binding strength of the dioxin to the surface, the water to the surface, and the dioxin to the water......... Posted by: Kevin      Read more         Source

August 21, 2007, 5:16 PM CT

High-speed Pulses Of Laser Light On Silicon

In the Sept. 3 issue of Optical Society of America's Optics Express, published online today, scientists announce that they have built the world's first "mode-locked silicon evanescent laser." Mode-locked evanescent lasers can deliver stable short pulses of laser light that are useful for a number of optical applications, including high-speed data transmission, multiple wavelength generation, remote sensing (LIDAR) and highly accurate optical clocks. This new work is a significant step toward the goal of combining lasers and other key optical components on silicon, providing a way to integrate optical and electronic functions on a single chip and enabling new types of integrated circuits. It introduces a more practical technology with lower cost, lower power consumption and more compact devices.Summary


Present-day computer technology depends on weak electrical currents for data communication within the silicon-based microprocessor. By causing silicon to emit light and exhibit other potentially useful optical properties, integration of photonic devices on silicon becomes possible. The problem in the past it is extremely difficult, nearly impossible, to create a laser in silicon.

Less than one year ago, a research team led by John Bowers at the University of California, Santa Barbara and Intel successfully created laser light from electrical current on silicon by placing a layer of indium phosphide (InP), an important technology in high-speed communication, above the silicon. In this new study, electrically-pumped lasers emitting 40 billion pulses of light per second were demonstrated, built on the hybrid silicon platform developed the year prior. This is the first-ever achievement of such a rate in silicon and one that matches the rates produced by other media in standard use today. These short pulses are composed of a number of evenly spaced colors of laser light, which could be separated and each used to transmit different high-speed information, replacing the need for hundreds of lasers with just one......... Posted by: Kevin      Read more         Source

August 20, 2007, 7:41 AM CT

Truly sick or simply scared?

Researchers at Pacific Northwest National Laboratory have discovered a way to increase the sensitivity of test strips that will enable creation of a portable biosensor that can address a major concern linked to incidents involving chemical or nerve agents - the need to quickly distinguish between individuals who have been exposed and the "worried well".

The sensor components resemble a pregnancy test strip and a small glucose testing meter. Its development will be discussed by principal investigator Yuehe Lin at the national meeting of the American Chemical Society.

Every disease has biomarkers, a change in the proteins that announces something is wrong. Lin and his team are creating a nanoparticle "label" that can increase the ability of a sensor to detect and interpret the message of biomarkers.

"Current test strip based-immunoassay technology has very good selectivity, but it can only give a positive or negative response," Lin said.

The scientists are working with an "electrochemical immunoassay approach." This involves using the antibody of a specific disease - a protein produced in response to an invading bacterium or other foreign substance - to attract the biomarker. Lin observed that labeling a second antibody with a nanoparticle amplifies the biomarker's signal. Greater amplification means more precise readings......... Posted by: Kevin      Read more         Source

August 16, 2007, 9:43 PM CT

Light seems to defy its own speed limit

IT'S a speed record that is supposed to be impossible to break. Yet two physicists are now claiming they have propelled photons faster than the speed of light. This would be in direct violation of a key tenet of Einstein's special theory of relativity that states that nothing, under any circumstance, can exceed the speed of light.

Gnter Nimtz and Alfons Stahlhofen of the University of Koblenz, Gera number of, have been exploring a phenomenon in quantum optics called photon tunnelling, which occurs when a particle slips across an apparently uncrossable barrier. The pair say they have now tunnelled photons "instantaneously" across a barrier of various sizes, from a few millimetres up to a metre. Their conclusion is that the photons traverse the barrier much faster than the speed of light.

To see how far they could make photons tunnel, Nimtz and Stahlhofen sandwiched two glass prisms together to make a cube 40 centimetres on its sides. Since photons tunnel most readily over distances comparable with their wavelength, the physicists used microwaves with a wavelength of 33 cm - long enough for large tunnelling distances yet still short enough that the photons' paths can be bent by the prism.

As expected, the microwaves shone straight through the cube, and when the prisms were separated, the first prism reflected the microwaves (see Diagram). However, in accordance with theory, a few microwave photons also tunnelled across the gap separating the two prisms, continuing as if the prisms were still sandwiched together......... Posted by: Kevin      Read more         Source

August 16, 2007, 8:41 PM CT

Nanoscale blasting adjusts resistance

A new process for adjusting the resistance of semiconductor devices by carpeting a small area of the device with tiny pits, like a yard dug up by demented terriers, may be the key to a new class of magnetic sensors, enabling new, ultra-dense data storage devices. The technique demonstrated by scientists at the National Institute of Standards and Technology (NIST)* allows engineers to tailor the electrical resistance of individual layers in a device without changing any other part of the processing or design.

The tiny magnetic sensors in modern disk drives are a sandwich of two magnetic layers separated by a thin buffer layer. The layer closest to the disk surface is designed to switch its magnetic polarity quickly in response to the direction of the magnetic bit recorded on the disk under it. The sensor works by measuring the electrical resistance across the magnetic layers, which changes depending on whether the two layers have matching polarities.

As manufacturers strive to make disk storage devices smaller and more densely packed with data, the sensors need to shrink as well, but current designs are starting to hit the wall. To meet the size constraints, prototype sensors measure sensor resistance perpendicular to the thin layers, but depending on the buffer material in the sensor, two different types of sensors can be made. Giant magneto-resistance (GMR) sensors use a low-resistance metal buffer layer and are fast, but plagued by very low, difficult to detect, signals. Conversely, magnetic tunnel junction (MTJ) sensors use a relatively high-resistance insulating buffer that delivers a strong signal, but has a slower response time, too slow to keep up with a very high-speed, high-capacity drive......... Posted by: Kevin      Read more         Source