Saturday, March 22, 2008

Smart Power

A smart grid could allow manufacturers more control over their power consumption.

Could the day come when manufacturers adjust their production schedules according to real-time electricity price rates? That's the hope of Gridwise Alliance, a consortium of automation and utility companies exploring technologies that will revolutionize the nation's electricity grid. While still in the development stages, the eventual goal is to utilize information technologies that will result in a "smart grid" that will provide flexible and adaptive power for all consumers.

For manufacturers, this might mean the ability to monitor electricity prices hourly, much like the stock market or an eBay auction, says David Hardin, technology officer for Invensys Process Systems Eastern Operations and a member of the Gridwise Architecture Council.

"Pricing information will be richer than it is now, and fluctuate more in real time, with fluctuating price information entering the manufacturing equation," explains Hardin. "Then, intelligent systems can take that information and do some online energy management relative to the pricing information that's coming from the utilities. So it adds another dimension to power management and energy management in a plant."

New Flexible Plastic Solar Panels Are Inexpensive And Easy To Make

Researchers at New Jersey Institute of Technology (NJIT) have developed an inexpensive solar cell that can be painted or printed on flexible plastic sheets. "The process is simple," said lead researcher and author Somenath Mitra, PhD, professor and acting chair of NJIT's Department of Chemistry and Environmental Sciences. "Someday homeowners will even be able to print sheets of these solar cells with inexpensive home-based inkjet printers. Consumers can then slap the finished product on a wall, roof or billboard to create their own power stations."

Harvesting energy directly from abundant solar radiation using solar cells is increasingly emerging as a major component of future global energy strategy, said Mitra. Yet, when it comes to harnessing renewable energy, challenges remain. Expensive, large-scale infrastructures such as wind mills or dams are necessary to drive renewable energy sources, such as wind or hydroelectric power plants. Purified silicon, also used for making computer chips, is a core material for fabricating conventional solar cells. However, the processing of a material such as purified silicon is beyond the reach of most consumers.

"Developing organic solar cells from polymers, however, is a cheap and potentially simpler alternative," said Mitra. "We foresee a great deal of interest in our work because solar cells can be inexpensively printed or simply painted on exterior building walls and/or roof tops. Imagine some day driving in your hybrid car with a solar panel painted on the roof, which is producing electricity to drive the engine. The opportunities are endless. "

The science goes something like this. When sunlight falls on an organic solar cell, the energy generates positive and negative charges. If the charges can be separated and sent to different electrodes, then a current flows. If not, the energy is wasted. Link cells electronically and the cells form what is called a panel, like the ones currently seen on most rooftops. The size of both the cell and panels vary. Cells can range from 1 millimeter to several feet; panels have no size limits.

The solar cell developed at NJIT uses a carbon nanotubes complex, which by the way, is a molecular configuration of carbon in a cylindrical shape. The name is derived from the tube's miniscule size. Scientists estimate nanotubes to be 50,000 times smaller than a human hair. Nevertheless, just one nanotube can conduct current better than any conventional electrical wire. "Actually, nanotubes are significantly better conductors than copper," Mitra added.

Mitra and his research team took the carbon nanotubes and combined them with tiny carbon Buckyballs (known as fullerenes) to form snake-like structures. Buckyballs trap electrons, although they can't make electrons flow. Add sunlight to excite the polymers, and the buckyballs will grab the electrons. Nanotubes, behaving like copper wires, will then be able to make the electrons or current flow.

"Using this unique combination in an organic solar cell recipe can enhance the efficiency of future painted-on solar cells," said Mitra. "Someday, I hope to see this process become an inexpensive energy alternative for households around the world."

"Fullerene single wall carbon nanotube complex for polymer bulk heterojunction photovoltaic cells," published June 21, 2007 in the Journal of Materials Chemistry by the Royal Society of Chemistry, details the process.

Adapted from materials provided by New Jersey Institute of Technology, via EurekAlert!, a service of AAAS.

NJIT researchers develop inexpensive, easy process to produce solar panels. (Credit: New Jersey Institute of Technology)

New Breath-Based Diagnostic

An innovative technique for detecting different biomarkers could result in a precise, easy-to-use diagnostic tool.

Telltale breath: Michael Thorpe, a graduate student at the University of Colorado, Boulder, holds part of a machine that uses optical techniques to analyze traces of chemicals on the breath. Inside the tube is a system of mirrors that exposes a subject’s breath to laser light. Light is absorbed by the breath according to its chemical composition. Credit: Jun Ye, JILA
People with cancer, asthma, and many other diseases carry trace amounts of distinctive biomarkers in their breath. Detecting these markers could allow doctors to diagnose such diseases in their early stages, noninvasively, and before symptoms arise. Existing techniques for analyzing the breath's chemical composition have limitations. Simple, relatively inexpensive methods can be imprecise; conversely, highly precise devices are complicated and expensive. Now, researchers at the University of Colorado, Boulder, and the National Institute of Standards and Technology are developing a sensitive optical technique for real-time breath analysis that may overcome some of these hurdles.

The new breath analyzer, developed by Jun Ye, a physics professor at the University of Colorado, uses a kind of laser light called an "optical frequency comb" to identify about a thousand compounds in a few seconds. Ye's system works by measuring how the breath absorbs light. The subject breathes into a tube that contains a laser, a system of mirrors, and a photodetector. The laser emits rapid pulses of light in frequencies ranging from infrared to visible. The light's frequency changes as it encounters compounds in the breath. The system analyses these changes determine which compounds are present.

The lungs have an intimate relationship with the blood: as a result, many volatile compounds from all over the body can be found in the breath. The best evidence of this comes from studies of lung and breast cancer and tuberculosis, says Michael Phillips, a medical doctor and CEO of Menssana Research, a company developing diagnostic breath tests. Currently, the Food and Drug Administration approves only two breath-analysis diagnostics. One uses nitric oxide levels to diagnose asthma; another, marketed by Menssana, analyzes hydrocarbon levels to predict a patient's likelihood of rejecting a heart transplant.

"For chemical analysis, optical techniques in general are the best you can get," says Margaret Ryan, principle investigator on the electronic nose project at NASA's Jet Propulsion Laboratory. But Ryan says since the sensitive optical breath analyzer has not been through clinical trials, it's not clear yet whether it will be better than existing techniques.

There are different approaches to detecting compounds on the breath, each of which has limitations, says Peter Mazzone, an oncologist at the Cleveland Clinic who's developing a breath test for lung cancer. (See "Lung-Cancer Breathalyzer.") Mass spectrometry, for example, uses sophisticated chemical analysis techniques to determine exactly what chemicals are in a breath sample, and at what concentrations. But this kind of approach can't be performed in a doctor's office: the equipment is expensive bulky, and requires specialists to operate. Moreover, mass spectrometry requires a concentration step. Before it can be analyzed, the breath must first be concentrated on a trap. This slows the process and, says Mazzone, may influence the results. "When breath chemicals have to be concentrated on some medium, then taken off the trap for analysis," something might be getting lost in the process, says Mazzone.

Other approaches are nonspecific. While such approaches tend to be cheaper and easier to use, Mazzone notes that they "don't tell concentrations or exactly what's there." Mazzone is currently developing his own nonspecific approach, which uses an array of dye spots that change color on contact with the breath. Certain color patterns are associated with certain diseases, but these color changes aren't traced back to the presence of particular chemicals on the breath.
Mazzone says Ye's optical system is a "step forward" towards developing a machine that can perform a detailed analysis using equipment that could be operated by a general practioner in their office. So far, says Ye, he's only used the optical frequency comb to identify simple molecules made up of moderate numbers of atoms. For example, the comb can detect nitric oxide, carbon monoxide, and pentane, all of which have been associated with asthma. More work is needed before the device can be used to identify what Ye calls "giant biomolecules." The light absorption signatures of these molecules will be more complex, but detecting them may expand the range of diseases that can be diagnosed with Ye's system, he says.

Combining semiconductors

Erik Bakkers, 34

Philips Research Laboratories

Combining semiconductors

Courtesy Erik Bakkers

See images of Erik Bakkers’s semiconductor nanowires

Silicon chips have revolutionized electronics, but for certain purposes, such as radio frequency transmission, chips made from compound semiconductors like gallium arsenide or indium phosphide work much better. Erik Bakkers of Philip­s Research Laboratories in Eindhoven, the Netherlands, has found a way to mix semi­conductors on a single chip.

Different semiconductors are normally incompatible, partly because they expand at different rates when heated. Combining them thus leads to physical strain that reduces performance. Bakkers solved the problem by building circuits out of nano­wires. Because the point of contact between the different semiconductors is small--just a few tens of nanometers--there is no strain.

To grow a nano­wire, Bakker­s places a gold nanoparticle on top of a silicon wafer. Then he exposes the wafer to a vapor of, say, ­gallium arsenide; the nano­particle cata­lyzes the growth of a gallium arsenide nanowire.

This technique opens up possibilities for multipurpose chips that could be used in wireless devices and other applications. It could also make it easier for engineers to take advantage of the inherent properties of compound semiconductors to create highly efficient LEDs, faster transistors, optical interconnects to rapidly shunt data around chips, or fast, highly sensitive biosensors to detect diseases.

Creating tumor-killing bacteria

J. Christopher Anderson, 31

University of California, Berkeley

Creating tumor-killing bacteria

Courtesy J. Christopher Anderson

Using the engineering approach of synthetic biology, Chris Anderson has set out to program bacteria to selectively kill cancer cells. He is combining DNA sequences from different types of bacteria and inserting them into the bacterium E. coli to create an organism that can evade the immune system, home in on tumors, and trick cancer cells into letting it inside, where it releases a toxin.

Anderson has built and tested all the biological parts for the cancer-­killing bug and is now working on putting them together. "All of these things exist as little genetic programs," he says. He also expects to be able to engineer bacteria for other medical purposes, because "everything is designed in a modular way, so the parts can be used for a totally different application that shares some of the same problems." For example, the genetic parts he has developed could be used to deliver medicine to an HIV-infected immune cell.

Credit: Tami Tolpa

1) Engineered bacteria are injected into the bloodstream; polysaccharide molecules on their surfaces allow them to evade the immune system

2) When they detect the low-oxygen environment of a tumor, the bacteria produce invasin, a protein that allows them to infiltrate the cancer cells

3) The invasin binds to the cancer cells, prompting the cells to engulf the bacteria

4) The cancer cell bursts the bacterium, releasing a toxic enzyme that kills the cell

Bacterial Battle Generates New Antibiotics

Scientists have revealed the hidden diversity of natural antibiotics using a new approach that pits one type of bacteria against another.

Bacterial battle: Scientists have discovered a new antibiotic, isolated from the bacterium Rhodococcus fascians. When dripped onto a paper disc (white) in the middle of a plate full of other bacteria (orange), the new antibiotic kills the bacteria.
Credit: Kazuhiko Kurosawa

Scientists at MIT encouraged bacteria to produce a novel antibiotic by pitting them against a microbial enemy. The newly discovered compound can kill H. pylori, bacteria linked to stomach ulcers. The approach could provide a new way to discover novel antibiotics and shed light on how and when bacteria churn out these toxic compounds.

"The lab is a tame place if you're a bacterium: you don't have to fight for a crystal of sugar," says Philip Lessard, a molecular biologist at MIT who collaborated on the work. "So maybe we're not seeing them spitting out chemical-warfare compounds like they would normally."

Antibacterial resistance--when bacteria become invincible to a particular drug--is becoming a major crisis in American hospitals. According to the Centers for Disease Control and Prevention, approximately two million Americans acquire infections while in hospitals every year, 90,000 of which are fatal. About 70 percent of those infections are resistant to at least one type of antibiotic.

Scientists across the globe are looking for ways to make new antibiotics. Some projects involve melding existing drugs into potent new molecules, while other approaches focus on designing new drugs that target specific mechanisms of microbial resistance. But recent sequencing studies suggest that bacteria possess an untapped well of novel antibiotics that they don't produce under normal lab conditions, thereby remaining hidden to scientists for decades.

Scientists working in Anthony Sinskey's lab at MIT sequenced the genome of a strain of soil-dwelling bacteria known as Rhodococcus fascians. They were surprised to find that this organism, not known for its antibiotic-producing powers, harbored a number of genes involved in the metabolism of antibiotic-like compounds. (In the wild, bacteria produce antibiotics as a survival mechanism, to clear themselves a niche in the crowded microbial world.)

While Rhodococcus seemed genetically capable of producing the compounds, the organisms did not do so in the lab--until, that is, they were grown alongside another type of bacteria, called Streptomyces, which are among the most prolific antibiotic producers in the microbial world. Microbiologist Kazuhiko Kurosawa and his colleagues published their discovery last month in the Journal of the American Chemical Society.

The novel compound, dubbed rhodostreptomycin, belongs to a class of antibiotics known as aminoglycosides, which include neomycin, used in many first-aid creams, and streptomycin, a tuberculosis drug. While it's unclear if the drug would be appropriate for clinical use, early tests show that it can kill H. pylori, bacteria linked to stomach ulcers, and it can survive highly acidic environments like that of the stomach. The molecule also appears to contain a novel structural component, which could provide a jumping-off point for chemists keen to design new drugs. "This opens a new domain in the chemical-diversity space," says Lessard.

Genetics' Role in Health Disparities

Charles Rotimi explains why a more complete snapshot of genetic variation is important.

Race and medicine: Charles Rotimi, a genetic epidemiologist, will head a new center at the National Institutes of Health to research diseases disproportionately affecting minority groups.
Credit: NHGRI

The last year has seen an explosion in studies linking specific genetic variations to common illnesses, such as diabetes and heart disease. But how common are these variations in different groups, and do they play the same role in different populations? Those are just two of the questions that genetic epidemiologist Charles Rotimi aims to answer as head of a new center devoted to the study of genetics, lifestyle, and disease in minority groups, at the National Institutes of Health, in Bethesda, MD.

Rotimi's research has focused on obesity, hypertension, and diabetes--three disorders that disproportionately affect African Americans; together, the high rates for these diseases account for more than 80 percent of the health disparities between African Americans and European Americans. The new Intramural Center for Genomics and Health Disparities will attempt to uncover the reasons for the differences by exploring the interactions between genetics and environment in African and African-American populations. While many disparities are clearly linked to socioeconomic factors and a lack of access to medical care, genetics may also play a vital role. A genetic vulnerability to hypertension or diabetes, for example, may only be realized in an environment with easy access to high-salt, high-fat foods. Genetic variations can also impact how well a drug works, or whether it will induce harmful side effects in the patient taking it. The variations can occur at different frequencies in different populations--something that needs to be taken into account when studying and prescribing new medicines.

Technology Review recently asked Rotimi to explain his work and its importance.

Technology Review: Why was the center created?

Charles Rotimi: We are right at the point where genomics is beginning to yield interesting fruits, and we want to see those fruits shared by all populations across the world.We want to take advantage of the fact that we are making considerable progress in understanding genetic variation and how it impacts the disease distribution we see across different populations. Only by including all populations can we truly understand human genetic variation and its importance for disease and response to drugs.

The center is set up to take advantage of all of these genomic tools, as well as to try to understand things like culture and lifestyle, and how they interact with genetics in terms of human disease. We want to look specifically at diseases that disproportionately affect minority groups in the United States, including obesity, hypertension, and diabetes.

We are trying to advance research into the role of culture, lifestyle, and genomics--not just genes, but the interactions between genes and environment--to help us understand common complex diseases. Because Africa is the original source of all human migration, whatever we find will be informative for the general population, not just the African people.

TR: Do you think the general public has a misconception about genetics and race?

CR: Yes. The misconception is that genetics can be used to unequivocally identify all members of a particular "race," compared to others. While it is true that, with enough genetic markers, it is possible to draw imprecise boundaries such as "Africans," "Europeans," and "Asians," there is no set of genetic markers that can be used to identify all persons that self-identify as belonging to a "racial" group without error.

Despite this, scientists have been unable to move beyond racial categorization in science, medicine, and society. Partially responsible for our continued obsession with race is the fact that, although we do not have distinct biological types of "races," we do have differences in the frequencies of genetic markers across human ancestral groups. These differences, which for the most part describe geographically distant populations, are believed to harbor the answers to why some individuals and groups may be more susceptible or resistant to diseases, and may also hold the key to understanding why certain groups respond differently to medications.