Wireless Heart Implant Reduces HospitalizationsA pressure-sensing implant helps heart-failure patients stay healthy.

Wireless Heart Implant Reduces HospitalizationsA pressure-sensing implant helps heart-failure patients stay healthy.

  10:29:00 AM    Science Lover

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A wireless sensor developed by Atlanta-based CardioMEMS reduced the number of hospitalizations in patients with heart failure by 39 percent. The tiny implant monitors fluid pressure in the pulmonary artery and transmits the data wirelessly to physicians, who can adjust patients' medications accordingly.

Researchers say the sensor may significantly lower health-care costs and improve quality of life for people with congestive heart failure. The device is one of several prototypes being developed by CardioMEMS and other medical implant companies to provide continuous, personalized wireless monitors for such patients.

Pressure patrol: A new wireless sensor the size of a paper
clip measures fluid pressure in the pulmonary artery. The
metalloops on either end anchor the sensor to the artery
walls, while the self-contained transducer in the middle
takes pressure readings. The sensor is activated by radio
frequency, transmitting data wirelessly to physicians
via modem.Credit: OSU Medical Center/CardioMEMS

"I think the study shows this kind of device is incredibly useful in improving outcomes in patients and directing therapy," says Marc Jay Semigran, medical director of the Mass General Heart Failure and Cardiac Transplant Program, who was not involved in the study.

Hospitals admit 1.1 million adults each year for congestive heart failure, a condition in which pressure builds up in the circulatory system and the heart fails to pump blood adequately to the rest of the body. The American Heart Association estimates that the chronic condition costs the health-care system $29 billion per year. CardioMEMS aims to reduce that figure by providing an accurate way to continuously monitor patients after they've left the hospital.

The device is implanted in the pulmonary artery, an area that carries a low risk of clotting. It is smaller than other implants under development because it does not require a battery or a wire to take pressure readings. Two metal loops hold it to the sides of the artery, and a pressure transducer records the flow of fluids through the blood vessel. The sensor is powered externally by a receiver built into a pillow. When a patient lies on the pillow, the sensor is activated to take measurements and send them wirelessly to a computer, where physicians can review the data. In a large six-month clinical trial published this month in the Lancet, 550 patients from 64 centers across the United States were equipped with the device and instructed to take readings once a day. Patients were divided into two groups. The first took medication instructions from physicians who monitored the sensor data. The second took instructions from physicians who relied on traditional indicators like weight and blood pressure. Over the six months, patients in the first group experienced 39 percent fewer hospitalizations than those in the second.

Today, physicians often assess pulmonary pressure when initially evaluating a patient, but they do so far less frequently in follow-up evaluation. That's because the measurement requires doctors to snake a catheter into a patient's heart and inflate a balloon. However, fluid pressure changes by the day, and monitoring those fluctuations continuously is essential to treating heart failure effectively.

"Over the years, we found that pressures go up long before patients develop symptoms and call a doctor to say they're sick," says Philip Adamson, director of the Heart Failure Institute at Oklahoma Heart Hospital, the principal investigator in the CardioMEMS clinical trial. "By utilizing the pressure sensor information, we're given the ability to make changes in medications long before patients bring themselves to the doctor, and that's how we reduced hospitalizations."

Over the past few years, several companies have jockeyed to be first on the market with a continuous pressure-sensing cardiac implant. In 2007, Medtronic failed to get FDA approval for its sensor, a stopwatch-size, battery-powered implant wired to the heart. The device reduced hospitalizations by 22 percent, but FDA regulators did not consider that worth the risks associated with implanting it. Researchers also found that the wire connecting the sensor to the heart degraded over time.

CardioMEMS is currently seeking approval for its sensor from the U.S. Food and Drug Administration and has submitted results from the clinical study for FDA review. In the next two or three years, the company plans to integrate the sensor's receiver into a patient's cell phone, which will be able to instantly read pressure data and upload it for both physicians and patients to review.

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Next-Generation Electronic Devices: Conduction, Surface States in Topological Insulator Nanoribbons Controlled

Next-Generation Electronic Devices: Conduction, Surface States in Topological Insulator Nanoribbons Controlled

  10:25:00 AM    Science Lover

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In recent years, topological insulators have become one of the hottest topics in physics. These new materials act as both insulators and conductors, with their interior preventing the flow of electrical currents while their edges or surfaces allow the movement of a charge.

Bismuth telluride nanoribbon crystalline structure. 
(Credit: Image courtesy of University 
of California - Los Angeles)

Perhaps most importantly, the surfaces of topological insulators enable the transport of spin-polarized electrons while preventing the "scattering" typically associated with power consumption, in which electrons deviate from their trajectory, resulting in dissipation.

Because of such characteristics, these materials hold great potential for use in future transistors, memory devices and magnetic sensors that are highly energy efficient and require less power.

In a study published Feb. 13 in Nature Nanotechnology, researchers from UCLA's Henry Samueli School of Engineering and Applied Science and from the materials division of Australia's University of Queensland show the promise of surface-conduction channels in topological insulator nanoribbons made of bismuth telluride and demonstrate that surface states in these nanoribbons are "tunable" -- able to be turned on and off depending on the position of the Fermi level.

"Our finding enables a variety of opportunities in building potential new-generation, low-dissipation nanoelectronic and spintronic devices, from magnetic sensing to storage," said Kang L. Wang, the Raytheon Professor of Electrical Engineering at UCLA Engineering, whose team carried out the research.

Bismuth telluride is well known as a thermoelectric material and has also been predicted to be a three-dimensional topological insulator with robust and unique surface states. Recent experiments with bismuth telluride bulk materials have also suggested two-dimensional conduction channels originating from the surface states. But it has been a great challenge to modify surface conduction, because of dominant bulk contribution due to impurities and thermal excitations in such small-band-gap semiconductors.

The development of topological insulator nanoribbons has helped. With their large surface-to-volume ratios, these nanoribbons significantly enhance surface conditions and enable surface manipulation by external means.

Wang and his team used thin bismuth telluride nanoribbons as conducting channels in field-effect transistor structures. These rely on an electric field to control the Fermi level and hence the conductivity of a channel. The researchers were able to demonstrate for the first time the possibility of controlling surface states in topological insulator nanostructures.

"We have demonstrated a clear surface conduction by partially removing the bulk conduction using an external electric field," said Faxian Xiu, a UCLA staff research associate and lead author of the study. "By properly tuning the gate voltage, very high surface conduction was achieved, up to 51 percent, which represents the highest values in topological insulators."

"This research is very exciting because of the possibility to build nanodevices with a novel operating principle," said Wang, who is also associate director of the California NanoSystems Institute (CNSI) at UCLA. "Very similar to the development of graphene, the topological insulators could be made into high-speed transistors and ultra-high-sensitivity sensors."

The new findings shed light on the controllability of the surface spin states in topological insulator nanoribbons and demonstrate significant progress toward high surface electric conditions for practical device applications. The next step for Wang's team is to produce high-speed devices based on their discovery.

"The ideal scenario is to achieve 100 percent surface conduction with a complete insulating state in the bulk," Xiu said. "Based on the current work, we are targeting high-performance transistors with power consumption that is much less than the conventional complementary metal-oxide semiconductors (CMOS) technology used typically in today's electronics."

Study collaborators Jin Zou, a professor of materials engineering at the University of Queensland; Yong Wang, a Queensland International Fellow; and Zou's team at the division of materials at the University of Queensland contributed significantly to this work. A portion of the research was also done in Alexandros Shailos' lab at UCLA.

The study was funded by the Focus Center Research Program -- Center on Functional Engineered Nano Architectonics (FENA) at UCLA Engineering; the U.S. Defense Advanced Research Projects Agency (DARPA); and the Australian Research Council. The research on topological insulators was pioneered by FENA's Shoucheng Zhang, a professor of physics at Stanford University.

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Watch 3D films on cellphone!

Watch 3D films on cellphone!

  1:55:00 AM    Science Lover

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Watching 3D films on your cellphone would now be possible thanks to researchers who have combined the new mobile radio standard LTE-advanced with a video coding technique.

Researchers at the Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut, HHI in Berlin, Germany, have come up with a special compression technique for films in especially good high-resolution HD quality.

Watching 3-D films on your cell 
phone would now be possible.

 

It computes the films down to low data rates while maintaining quality: H.264/AVC. What the H.246/AVC video format is to high-definition films, the Multiview Video Coding (MVC) is to 3D films.

Thomas Schierl explained that "MVC is used to pack together the two images needed for the stereoscopic 3D effect to measurably reduce the film's bit rate," and this technique can be used to reduce the size of 3D films as much as 40 per cent.

That means that you can quickly receive excellent quality 3-D films in connection with the new 3G-LTE mobile radio standard. Key is the radio resource management integrated into the LTE system that allows flexible data transmission while including various quality of service classes.

Thomas Wirth, another scientist at the HHI, added, "The 2D and 3D bit streams divided up by MVC can be prioritized for each user at the air interface to support different services, thus opening up a completely new field for business models."

The new technology would be shown at the Mobile World Congress in Barcelona

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New Solar Cell Self-Repairs Like Natural Plant Systems

New Solar Cell Self-Repairs Like Natural Plant Systems

  10:09:00 AM    Science Lover

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Researchers are creating a new type of solar cell designed to self-repair like natural photosynthetic systems in plants by using carbon nanotubes and DNA, an approach aimed at increasing service life and reducing cost.

Jong Hyun Choi, an assistant professor of mechanical 
engineering at Purdue, and doctoral student Benjamin 
Baker use fluorescent imaging to view a carbon nanotube. 
Their research is aimed at creating a new type of solar 
cell designed to self-repair like natural photosynthetic 
systems. The approach might enable researchers 
to increase the service life and reduce costs for 
photoelectrochemical cells, which convert sunlight 
into electricity. (Credit: Purdue University 
photo/Mark Simons)

"We've created artificial photosystems using optical nanomaterials to harvest solar energy that is converted to electrical power,"said Jong Hyun Choi, an assistant professor of mechanical engineering at Purdue University.

The design exploits the unusual electrical properties of structures called single-wall carbon nanotubes, using them as "molecular wires in light harvesting cells," said Choi, whose research group is based at the Birck Nanotechnology and Bindley Bioscience centers at Purdue's Discovery Park.

"I think our approach offers promise for industrialization, but we're still in the basic research stage," he said.

Photoelectrochemical cells convert sunlight into electricity and use an electrolyte -- a liquid that conducts electricity -- to transport electrons and create the current. The cells contain light-absorbing dyes called chromophores, chlorophyll-like molecules that degrade due to exposure to sunlight.

"The critical disadvantage of conventional photoelectrochemical cells is this degradation," Choi said.

The new technology overcomes this problem just as nature does: by continuously replacing the photo-damaged dyes with new ones.

"This sort of self-regeneration is done in plants every hour," Choi said.

The new concept could make possible an innovative type of photoelectrochemical cell that continues operating at full capacity indefinitely, as long as new chromophores are added.

Findings were detailed in a November presentation during the International Mechanical Engineering Congress and Exhibition in Vancouver. The concept also was unveiled in an online article (http://spie.org/x41475.xml?ArticleID=x41475) featured on the Web site for SPIE, an international society for optics and photonics.

The talk and article were written by Choi, doctoral students Benjamin A. Baker and Tae-Gon Cha, and undergraduate students M. Dane Sauffer and Yujun Wu.

The carbon nanotubes work as a platform to anchor strands of DNA. The DNA is engineered to have specific sequences of building blocks called nucleotides, enabling them to recognize and attach to the chromophores.

"The DNA recognizes the dye molecules, and then the system spontaneously self-assembles," Choi said

When the chromophores are ready to be replaced, they might be removed by using chemical processes or by adding new DNA strands with different nucleotide sequences, kicking off the damaged dye molecules. New chromophores would then be added.

Two elements are critical for the technology to mimic nature's self-repair mechanism: molecular recognition and thermodynamic metastability, or the ability of the system to continuously be dissolved and reassembled.

The research is an extension of work that Choi collaborated on with researchers at the Massachusetts Institute of Technology and the University of Illinois. The earlier work used biological chromophores taken from bacteria, and findings were detailed in a research paper published in November in the journal Nature Chemistry (http://www.nature.com/nchem/journal/v2/n11/abs/nchem.822.html).

However, using natural chromophores is difficult, and they must be harvested and isolated from bacteria, a process that would be expensive to reproduce on an industrial scale, Choi said.

"So instead of using biological chromophores, we want to use synthetic ones made of dyes called porphyrins," he said.

Photosynthesis III: Photosynthetic Membranes and Light Harvesting Systems (Encyclopedia of Plant Physiology) (Volume 3)

Photosynthetic Light-Harvesting Systems: Organization and Function. Proceedings of an International Workshop October 12-16, 1987. Freising, Fed. Rep.

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Brain's Electrical Fields: Neural Communication

Brain's Electrical Fields: Neural Communication

  8:57:00 PM    Science Lover

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The brain -- awake and sleeping -- is awash in electrical activity, and not just from the individual pings of single neurons communicating with each other. In fact, the brain is enveloped in countless overlapping electric fields, generated by the neural circuits of scores of communicating neurons. The fields were once thought to be an "epiphenomenon, a 'bug' of sorts, occurring during neural communication," says neuroscientist Costas Anastassiou, a postdoctoral scholar in biology at the California Institute of Technology (Caltech).

Ephaptic coupling leads to coordinated spiking 
of nearby neurons, as measured using a 12-pipette 
electrophysiology setup developed in the laboratory of 
coauthor Henry Markram. (Credit: Image from 
Figure 4 in Anastassiou et., Nature Neuroscience, 2011)

New work by Anastassiou and his colleagues, however, suggests that the fields do much more -- and that they may, in fact, represent an additional form of neural communication.

"In other words," says Anastassiou, the lead author of a paper about the work appearing in the journal Nature Neuroscience, "while active neurons give rise to extracellular fields, the same fields feed back to the neurons and alter their behavior," even though the neurons are not physically connected -- a phenomenon known as ephaptic coupling. "So far, neural communication has been thought to occur at localized machines, termed synapses. Our work suggests an additional means of neural communication through the extracellular space independent of synapses."

Extracellular electric fields exist throughout the living brain, though they are particularly strong and robustly repetitive in specific brain regions such as the hippocampus, which is involved in memory formation, and the neocortex, the area where long-term memories are held. "The perpetual fluctuations of these extracellular fields are the hallmark of the living and behaving brain in all organisms, and their absence is a strong indicator of a deeply comatose, or even dead, brain," Anastassiou explains.

Previously, neurobiologists assumed that the fields were capable of affecting -- and even controlling -- neural activity only during severe pathological conditions such as epileptic seizures, which induce very strong fields. Few studies, however, had actually assessed the impact of far weaker -- but very common -- non-epileptic fields. "The reason is simple," Anastassiou says. "It is very hard to conduct an in vivo experiment in the absence of extracellular fields," to observe what changes when the fields are not around.

To tease out those effects, Anastassiou and his colleagues, including Caltech neuroscientist Christof Koch, the Lois and Victor Troendle Professor of Cognitive and Behavioral Biology and professor of computation and neural systems, focused on strong but slowly oscillating fields, called local field potentials (LFP), that arise from neural circuits composed of just a few rat brain cells. Measuring those fields and their effects required positioning a cluster of tiny electrodes within a volume equivalent to that of a single cell body -- and at distances of less than 50 millionths of a meter from one another.

"Because it had been so hard to position that many electrodes within such a small volume of brain tissue, the findings of our research are truly novel," Anastassiou says. Previously, he explains, "nobody had been able to attain this level of spatial and temporal resolution."

An "unexpected and surprising finding was how already very weak extracellular fields can alter neural activity," he says. "For example, we observed that fields as weak as one millivolt per millimeter robustly alter the firing of individual neurons, and increase the so-called "spike-field coherence" -- the synchronicity with which neurons fire with relationship to the field."In the mammalian brain, we know that extracellular fields may easily exceed two to three millivolts per millimeter. Our findings suggest that under such conditions, this effect becomes significant."

What does that mean for brain computation? "Neuroscientists have long speculated about this," Anastassiou says. "Increased spike-field coherency may substantially enhance the amount of information transmitted between neurons as well as increase its reliability. Moreover, it has been long known that brain activity patterns related to memory and navigation give rise to a robust LFP and enhanced spike-field coherency. We believe ephaptic coupling does not have one major effect, but instead contributes on many levels during intense brain processing."

Can external electric fields have similar effects on the brain? "This is an interesting question," Anastassiou says. "Indeed, physics dictates that any external field will impact the neural membrane. Importantly, though, the effect of externally imposed fields will also depend on the brain state. One could think of the brain as a distributed computer -- not all brain areas show the same level of activation at all times.

"Whether an externally imposed field will impact the brain also depends on which brain area is targeted. During epileptic seizures, pathological fields can be as strong as 100 millivolts per millimeter¬ -- such fields strongly entrain neural firing and give rise to super-synchronized states." And that, he adds, suggests that electric field activity -- even from external fields -- in certain brain areas, during specific brain states, may have strong cognitive and behavioral effects.

Ultimately, Anastassiou, Koch, and their colleagues would like to test whether ephaptic coupling affects human cognitive processing, and under which circumstances. "I firmly believe that understanding the origin and functionality of endogenous brain fields will lead to several revelations regarding information processing at the circuit level, which, in my opinion, is the level at which percepts and concepts arise," Anastassiou says. "This, in turn, will lead us to address how biophysics gives rise to cognition in a mechanistic manner -- and that, I think, is the holy grail of neuroscience."

The work in the paper was supported by the Engineering Physical Sciences Research Council, the Sloan-Swartz Foundation, the Swiss National Science Foundation, EU Synapse, the National Science Foundation, the Mathers Foundation, and the National Research Foundation of Korea.

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'Tall Order' Sunlight-to-Hydrogen System Works, Neutron Analysis Confirms

'Tall Order' Sunlight-to-Hydrogen System Works, Neutron Analysis Confirms

  10:28:00 AM    Science Lover

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Researchers at the Department of Energy's Oak Ridge National Laboratory have developed a biohybrid photoconversion system -- based on the interaction of photosynthetic plant proteins with synthetic polymers -- that can convert visible light into hydrogen fuel.

Neutron scattering analysis performed at DOE's Oak Ridge 
National Laboratory reveals the lamellar structure of a 
hydrogen-producing, biohybrid composite material formed 
by the self-assembly of naturally occurring, light harvesting 
proteins with polymers. (Credit: Image courtesy of 
DOE/Oak Ridge National Laboratory)

Photosynthesis, the natural process carried out by plants, algae and some bacterial species, converts sunlight energy into chemical energy and sustains much of the life on earth. Researchers have long sought inspiration from photosynthesis to develop new materials to harness the sun's energy for electricity and fuel production.

In a step toward synthetic solar conversion systems, the ORNL researchers have demonstrated and confirmed with small-angle neutron scattering analysis that light harvesting complex II (LHC-II) proteins can self-assemble with polymers into a synthetic membrane structure and produce hydrogen.

The researchers envision energy-producing photoconversion systems similar to photovoltaic cells that generate hydrogen fuel, comparable to the way plants and other photosynthetic organisms convert light to energy.

"Making a, self-repairing synthetic photoconversion system is a pretty tall order. The ability to control structure and order in these materials for self-repair is of interest because, as the system degrades, it loses its effectiveness," ORNL researcher Hugh O'Neill, of the lab's Center for Structural Molecular Biology, said.

"This is the first example of a protein altering the phase behavior of a synthetic polymer that we have found in the literature. This finding could be exploited for the introduction of self-repair mechanisms in future solar conversion systems," he said.

Small angle neutron scattering analysis performed at ORNL's High Flux Isotope Reactor (HFIR) showed that the LHC-II, when introduced into a liquid environment that contained polymers, interacted with polymers to form lamellar sheets similar to those found in natural photosynthetic membranes.

The ability of LHC-II to force the assembly of structural polymers into an ordered, layered state -- instead of languishing in an ineffectual mush -- could make possible the development of biohybrid photoconversion systems. These systems would consist of high surface area, light-collecting panes that use the proteins combined with a catalyst such as platinum to convert the sunlight into hydrogen, which could be used for fuel.

The research builds on previous ORNL investigations into the energy-conversion capabilities of platinized photosystem I complexes -- and how synthetic systems based on plant biochemistry can become part of the solution to the global energy challenge.

"We're building on the photosynthesis research to explore the development of self-assembly in biohybrid systems. The neutron studies give us direct evidence that this is occurring," O'Neill said.

The researchers confirmed the proteins' structural behavior through analysis with HFIR's Bio-SANS, a small-angle neutron scattering instrument specifically designed for analysis of biomolecular materials.

"Cold source" neutrons, in which energy is removed by passing them through cryogenically chilled hydrogen, are ideal for studying the molecular structures of biological tissue and polymers.

The LHC-II protein for the experiment was derived from a simple source: spinach procured from a local produce section, then processed to separate the LHC-II proteins from other cellular components. Eventually, the protein could be synthetically produced and optimized to respond to light.

O'Neill said the primary role of the LHC-II protein is as a solar collector, absorbing sunlight and transferring it to the photosynthetic reaction centers, maximizing their output. "However, this study shows that LHC-II can also carry out electron transfer reactions, a role not known to occur in vivo," he said.

The research team, which came from various laboratory organizations including its Chemical Sciences Division, Neutron Scattering Sciences Division, the Center for Structural Molecular Biology and the Center for Nanophase Materials Sciences, consisted of O'Neill, William T. Heller, and Kunlun Hong, all of ORNL; Dimitry Smolensky of the University of Tennessee; and Mateus Cardoso, a former postdoctoral researcher at ORNL now of the Laboratio Nacional de Luz Sincrotron in Brazil.

"That's one of the nice things about working at a national laboratory. Expertise is available from a variety of organizations," O'Neill said.

The work, published in the journal Energy & Environmental Science, was supported with Laboratory-Directed Research and Development funding. HFIR is supported by the DOE Office of Science.

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Human Genome's Breaking Points: Genetic Sequence of Large-Scale Differences Between Human Genomes

Human Genome's Breaking Points: Genetic Sequence of Large-Scale Differences Between Human Genomes

  10:04:00 AM    Science Lover

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A detailed analysis of data from 185 human genomes sequenced in the course of the 1000 Genomes Project, by scientists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, in collaboration with researchers at the Wellcome Trust Sanger Institute in Cambridge, UK, as well as the University of Washington and Harvard Medical School, both in the USA, has identified the genetic sequence of an unprecedented 28 000 structural variants (SVs) -- large portions of the human genome which differ from one person to another.

The work, published in Nature, could help find the genetic causes of some diseases and also begins to explain why certain parts of the human genome change more than others.

Scientists have identified the genetic sequence of an unprecedented 28,000 structural variants -- large portions of the human genome which differ from one person to another. (Credit: iStockphoto/Andrey Prokhorov)

The international team of scientists identified over a thousand SVs that disrupt the sequence of one or more genes. These gene-altering mutations may be linked to diseases, so knowing the exact genetic sequence of these variations will help clinical geneticists to narrow down their searches for disease-causing mutations.

"Knowing the exact genetic sequence of SVs and their context in the genome could help find the genetic causes for as-yet unexplained diseases," says Jan Korbel, who led the research at EMBL: "this may help us understand why some people remain healthy until old age whereas others develop diseases early in their lives."

This unprecedented catalogue of large-scale genetic variants also sheds light on why some parts of the genome mutate more frequently than others. The scientists found that deletions, where genetic material is lost, and insertions, where it is gained, tend to happen in different places in the genome and through different molecular processes. For instance, large-scale deletions are more likely to occur in regions where DNA often breaks and has to be put back together, as 'chunks' of genetic material can be lost in the process.

"We found 51 hotspots where certain SVs, such as large deletions, appear to occur particularly often" Korbel says: "Six of those hotspots are in regions known to be related to genetic conditions such as Miller-Dieker syndrome, a congenital brain disease that can lead to infant death."

Previous research had already linked SVs -- also called copy-number variants -- to many genetic conditions, such as colour-blindness, schizophrenia, and certain forms of cancer. However, because of their large size and complex DNA sequence, SVs were difficult to identify. In this study, the researchers overcame these difficulties, developing novel computational approaches that allowed them to pinpoint the exact locations of these large-scale variations in the genome, broadening the potential scope of future disease studies.

"There are many structural variants in everyone's genomes and they are increasingly being associated with various aspects of human health" says Charles Lee, a clinical cytogeneticist and associate professor at Harvard Medical School and Brigham and Women's Hospital, and joint leader of the study: "It is important to be able to identify and comprehensively characterize these genetic variants using state-of-the-art DNA sequencing technologies."

Data from this study is being made publicly available to the scientific community through the 1000 Genomes Project, an international public-private consortium to build the most detailed map of human genetic variation to date. The 1000 Genomes Project aims to sequence 2500 whole genomes by the end of 2012, resulting, by far, in the largest collection of human genomes to date.

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New Way to Harvest Energy from Sunlight

New Way to Harvest Energy from Sunlight

  9:37:00 AM    Science Lover

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Professor Richard Watt and his chemistry students suspected that a common protein could potentially react with sunlight and harvest its energy -- similar to what chlorophyll does during photosynthesis.

BYU chemistry professor Richard Watt. (Credit: Image courtesy of Brigham Young University)

The story of how they proved it sounds as colorful as the legend of the leprechaun who hid his pot of gold at the end of the rainbow.

They started with citric acid from oranges and mixed it with the protein. Next they dissolved gold powder into the solution. Then they put vials of the yellow-colored mixture in direct sunlight and crossed their fingers in the hope that it would turn purple.

Here's the reason why: If it turned purple, that would signal that the gold atoms had received electrons and used the donated energy to bunch together as small, purple-colored nanoparticles. And that would mean that the protein used the sunlight to excite the citric acid and trigger a transfer of energy.

While direct sunlight did the trick in about 20 minutes, a high-powered tungsten mercury lamp worked much faster.

"We set the system up, turned on the light, and the solution turned purple," Watt said. "We knew that we'd proved the concept."

The beauty of this experiment lies not in its colors -- unless, of course, you're thinking of it as a potential "green" energy source that keeps the environment clean.

The BYU researchers published their experiments in the Journal of Nanoparticle Research. The final step of this project will involve connecting the protein to an electrode to channel the energy into a battery or fuel cell. The BYU chemists will partner with Jae-Woo Kim of the National Institute of Aerospace for this next stage of the work.

Professor Watt's pedigree includes a post-doc at Princeton, a father who developed a fuel cell that runs on sugar and weed-killer and a more distant ancestor credited with inventing the first practical steam engine. That ancestor is also the Scottish engineer for whom the unit of power "watt" is named.

Co-authors on the new study include BYU graduate Jeremiah Keyes, grad student Robert Hilton and Jeff Farrer, who runs an electron microscope lab at BYU.

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New Reactor to Make Fuel from Sunlight

New Reactor to Make Fuel from Sunlight

  8:13:00 PM    Science Lover

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Using a common metal most famously found in self-cleaning ovens, Sossina Haile hopes to change our energy future. The metal is cerium oxide -- or ceria -- and it is the centerpiece of a promising new technology developed by Haile and her colleagues that concentrates solar energy and uses it to efficiently convert carbon dioxide and water into fuels.

Sossina Haile and William Chueh stand next to the 
benchtop thermochemical reactor used to screen 
materials for implementation on the solar reactor. 
(Credit: Courtesy of Caltech)

Solar energy has long been touted as the solution to our energy woes, but while it is plentiful and free, it can't be bottled up and transported from sunny locations to the drearier -- but more energy-hungry -- parts of the world. The process developed by Haile -- a professor of materials science and chemical engineering at the California Institute of Technology (Caltech) -- and her colleagues could make that possible.

The researchers designed and built a two-foot-tall prototype reactor that has a quartz window and a cavity that absorbs concentrated sunlight. The concentrator works "like the magnifying glass you used as a kid" to focus the sun's rays, says Haile.

At the heart of the reactor is a cylindrical lining of ceria. Ceria -- a metal oxide that is commonly embedded in the walls of self-cleaning ovens, where it catalyzes reactions that decompose food and other stuck-on gunk -- propels the solar-driven reactions. The reactor takes advantage of ceria's ability to "exhale" oxygen from its crystalline framework at very high temperatures and then "inhale" oxygen back in at lower temperatures.

"What is special about the material is that it doesn't release all of the oxygen. That helps to leave the framework of the material intact as oxygen leaves," Haile explains. "When we cool it back down, the material's thermodynamically preferred state is to pull oxygen back into the structure."

Specifically, the inhaled oxygen is stripped off of carbon dioxide (CO2) and/or water (H2O) gas molecules that are pumped into the reactor, producing carbon monoxide (CO) and/or hydrogen gas (H2). H2 can be used to fuel hydrogen fuel cells; CO, combined with H2, can be used to create synthetic gas, or "syngas," which is the precursor to liquid hydrocarbon fuels. Adding other catalysts to the gas mixture, meanwhile, produces methane. And once the ceria is oxygenated to full capacity, it can be heated back up again, and the cycle can begin anew.

For all of this to work, the temperatures in the reactor have to be very high -- nearly 3,000 degrees Fahrenheit. At Caltech, Haile and her students achieved such temperatures using electrical furnaces. But for a real-world test, she says, "we needed to use photons, so we went to Switzerland." At the Paul Scherrer Institute's High-Flux Solar Simulator, the researchers and their collaborators -- led by Aldo Steinfeld of the institute's Solar Technology Laboratory -- installed the reactor on a large solar simulator capable of delivering the heat of 1,500 suns.

In experiments conducted last spring, Haile and her colleagues achieved the best rates for CO2 dissociation ever achieved, "by orders of magnitude," she says. The efficiency of the reactor was uncommonly high for CO2 splitting, in part, she says, "because we're using the whole solar spectrum, and not just particular wavelengths." And unlike in electrolysis, the rate is not limited by the low solubility of CO2 in water. Furthermore, Haile says, the high operating temperatures of the reactor mean that fast catalysis is possible, without the need for expensive and rare metal catalysts (cerium, in fact, is the most common of the rare earth metals -- about as abundant as copper).

In the short term, Haile and her colleagues plan to tinker with the ceria formulation so that the reaction temperature can be lowered, and to re-engineer the reactor, to improve its efficiency. Currently, the system harnesses less than 1% of the solar energy it receives, with most of the energy lost as heat through the reactor's walls or by re-radiation through the quartz window. "When we designed the reactor, we didn't do much to control these losses," says Haile. Thermodynamic modeling by lead author and former Caltech graduate student William Chueh suggests that efficiencies of 15% or higher are possible.

Ultimately, Haile says, the process could be adopted in large-scale energy plants, allowing solar-derived power to be reliably available during the day and night. The CO2 emitted by vehicles could be collected and converted to fuel, "but that is difficult," she says. A more realistic scenario might be to take the CO2 emissions from coal-powered electric plants and convert them to transportation fuels. "You'd effectively be using the carbon twice," Haile explains. Alternatively, she says, the reactor could be used in a "zero CO2 emissions" cycle: H2O and CO2 would be converted to methane, would fuel electricity-producing power plants that generate more CO2 and H2O, to keep the process going.

The work was funded by the National Science Foundation, the State of Minnesota Initiative for Renewable Energy and the Environment, and the Swiss National Science Foundation.

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Birds of a feather? Your genes help you select friends

Birds of a feather? Your genes help you select friends

  10:25:00 AM    Science Lover

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Vices attract while virtues repel people, according to a new study, which has found that genetic make-up plays a part in who one chooses as friends.

Researchers have found that people partly choose their friends by their genes especially those that have a big impact on their behaviour sometimes it can be a case of "opposites attract'' while sometimes "birds of a feather flock together". To research the conclusion, a team, led by James Fowler at University of California, used data from two large health studies to search for genetic links to friendship.

OF HUMAN BONDAGE

The researchers identified genetic markers, or genotypes, in six specific genes and looked at how often they occurred among friends. They found two clear examples where "birds of a feather flock together" and "opposites attract". The first involved a variant of the gene DRD2 which has been associated with alcoholism. People who carried the DRD2 genotype tended to befriend others with the same marker. Those who lacked the marker were also more likely to be friends with one another.

A less obvious opposite association was seen between people with a version of the gene CYP2A6linked to having an "open" personality. In this case, people with the genetic marker gravitated towards individuals who did not have it.

The findings, published in the 'Proceedings of the National Academy of Sciences' journal, remained significant after taking account of people's tendency to form "local" friendships within the same geographical area.

"An important implication of these results is that genetic structure in human populations may result not only from the formation of reproductive unions, but also from the formation of friendship unions within• a population," said the researchers in a statement on Tuesday.

Human evolution may to some extent have been shaped by interactions between genes and friendship choices." The human evolutionary environment is not limited to the physical and biological environment, but also includes the social environment, which may itself be an evolutionary force," they Said.

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