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The catalyst, which is made of molybdenum disulphide nanoparticles grown on graphene, might be a real alternative to expensive platinum in future large-scale industrial and domestic applications.

Hydrogen could be an environmentally friendly alternative to conventional fossil fuels, particularly if it is electrochemically produced from ordinary seawater – a huge and abundantly available resource. However, before this can happen, scientists need to make advanced catalysts that increase the efficiency of the electrochemical hydrogen reaction (HER). Today, the most efficient HER catalysts are those made from platinum-group metals, but these are expensive.

Now, Hongjie Dai and colleagues have shown that flexible graphene oxide sheets could provide an ideal substrate for MoS2 nanoparticles. The resulting MoS2/reduced graphene oxide hybrid has a very high electrocatalytic activity for the HER that is superior to MoS2 catalysts synthesized without graphene.

 (A) Schematic solvothermal synthesis with GO sheets to afford the MoS2/RGO hybrid. (B) SEM and (inset) TEM images of the MoS2/RGO hybrid. (C) Schematic solvothermal synthesis without any GO sheets, resulting in large, free MoS2 particles. (D) SEM and (inset) TEM images of the free particles. Courtesy: JACS

(A) Schematic solvothermal synthesis with GO sheets to afford the MoS2/RGO hybrid. (B) SEM and (inset) TEM images of the MoS2/RGO hybrid. (C) Schematic solvothermal synthesis without any GO sheets, resulting in large, free MoS2 particles. (D) SEM and (inset) TEM images of the free particles. Courtesy: JACS

Catalytic edge sites

Indeed, the researches have measured a HER "Tafel slope" (which indicates the rate of a electrochemical reaction) of 41 mV/decade – a value that far exceeds the activity of previous MoS2 catalysts. This value results from the large number of catalytic edge sites on the tiny MoS2 nanoparticles and the fact that the material couples well to the underlying graphene network.

And that's not all: the hybrid catalyst also has a small overpotential, a large current density and it remains active even after 1000 cycles. "Traditional catalysts such as platinum and palladium, although very efficient, are pricey," Dai told nanotechweb.org. "Given the performance and low cost of the MoS2/RGO hybrid catalyst reported in our paper, we could foresee a possible replacement of these precious metals in future large-scale industrial and domestic applications."

The Stanford researchers made their hybrid catalysts in a solvothermal reaction of ammonium tetrathiomolybdate – (NH4)MoS4 – and hydrazine in a dimethylformaide solution of graphene oxide at 200 °C overnight. During this process, graphene oxide was reduced to RGO, and (NH4)MoS4 was reduced to MoS2on RGO by hydrazine.

"We are now working on improving our catalyst and possibly integrating it into photoelectrochemical reactions," revealed Dai.

The work was published in the Journal of the American Chemical Society.

Source: NanoTechWeb

 

Now, a team of head and neck surgeons from Mayo Clinic has found robotic surgery can treat cancer in the narrow, hard-to-reach area beyond the tongue at the top of the voice box. Some patients were able to avoid further treatment with chemotherapy or radiation, and most could resume normal eating and speaking.

"We've known it's useful for tongue base and tonsil cancers, but we wanted to assess its effectiveness in the larynx," says Kerry Olsen, M.D., Mayo Clinic otolaryngologist and senior author of the study that was presented April 29 at the Combined Otolaryngological Spring Meetings in Chicago.

The investigation of transoral robotic surgery (TORS) followed nine patients for up to three years following removal of supraglottic squamous cell carcinoma, which affects the area of the larynx above the vocal cords. Most of the patients had advanced-stage disease. The results showed TORS effectively removed cancer, with "clean," disease-free margins, and was easier to perform than the approach of transoral laser microsurgery via a laryngoscope. The patients also underwent the surgical removal of their adjacent neck nodes at the same operation.

"We were pleased with the cancer outcomes," Dr. Olsen says. "We also found patients had minimal trouble after surgery, in most cases resuming normal eating, swallowing and speaking."

With TORS, the robotic arms that enter the mouth include a thin camera, an arm with a cautery or laser, and an arm with a gripping tool to retract and grasp tissue. The surgeon sits at a console, controlling the instruments and viewing the three-dimensional surgical field on a screen. "The camera improves visibility," Dr. Olsen says. "We also gain the ability to maneuver and see around corners and into tight spaces, and we believe we'll now be able to take out more throat tumors than with traditional approaches of the past."

The new application of TORS comes at the right time, Dr. Olsen notes. Cancers of the tongue and throat are on the rise. Not all patients will be candidates for robotic surgery; its use will depend on the architecture of a patient's throat and neck, along with the type and extent of the tumor. "What we know from this study is that for larynx cancer, we have another effective surgical tool available to us," he says. "We can further tailor the cancer treatment for each patient and provide individualized care."

Source: ScienceDaily

 

A new kind of sensor could warn emergency workers when carbon filters in the respirators they wear to avoid inhaling toxic fumes have become dangerously saturated.

In a recent issue of the journal Advanced Materials, a team of researchers from the University of California, San Diego and Tyco Electronics describe how they made the carbon nanostructures and demonstrate their potential use as microsensors for volatile organic compounds.

IMAGE: Porous photonic crystal microsensor particles on the ends of optical fibers can detect organic pollutants.

First responders protect themselves from such vapors, whose composition is often unknown, by breathing through a canister filled with activated charcoal – a gas mask. Airborne toxins stick to the carbon in the filter, trapping the dangerous materials.

As the filters become saturated, chemicals will begin to pass through. The respirator can then do more harm than good by providing an illusion of safety. But there is no easy way to determine when the filter is spent. Current safety protocols base the timing of filter changes on how long the user has worn the mask.

"The new sensors would provide a more accurate reading of how much material the carbon in the filters has actually absorbed," said team leader Michael Sailor, professor of chemistry and biochemistry and bioengineering at UC San Diego. "Because these carbon nanofibers have the same chemical properties as the activated charcoal used in respirators, they have a similar ability to absorb organic pollutants."

Sailor's team assembled the nanofibers into repeating structures called photonic crystals that reflect specific wavelengths, or colors, of light. The wing scales of the Morpho butterfly, which give the insect its brilliant iridescent coloration, are natural examples of this kind of structure.

Caption: Repeating bands of greater density give this bundle of carbon nanofiber photonic crystals a characteristic color. When the porous fibers absorb chemicals, they change color, making the material a sensitive optical sensor for chemical vapors.

Credit: Timothy Kelly, UCSD Chemistry and Biochemistry

The sensors are an iridescent color too, rather than black like ordinary carbon. That color changes when the fibers absorb toxins – a visible indication of their capacity for absorbing additional chemicals.

The agency that certifies respirators in the U.S., the National Institute of Occupational Safety and Health, has long sought such a sensor but the design requirements for a tiny, sensitive, inexpensive device that requires little power, have proved difficult to meet.

The materials that the team fabricated are very thin – less than half the width of a human hair. Sailor's group has previously placed similar photonic sensors on the tips of optical fibers less than a millimeter across and shown that they can be inserted into respirator cartridges. And the crystals are sensitive enough to detect chemicals such as toluene at concentrations as low as one part per million.

Source: EurekAlert

 

The question they may want to ask instead is how can they prevent their child from becoming a bully.

New research to be presented on Sunday, May 1, at the Pediatric Academic Societies (PAS) annual meeting in Denver shows that parents can play a key role in decreasing the chances that their son or daughter will harass or intimidate other children.

Researchers, led by Rashmi Shetgiri, MD, FAAP, examined the prevalence of bullying reported by parents who took part in the National Survey of Children's Health from 2003-2007. They also looked at factors that were associated with an increased or decreased risk that a child bullied others.

The survey showed nearly one in six youths 10-17 years old bullied others frequently in 2007, according to Dr. Shetgiri, assistant professor of pediatrics at University of Texas Southwestern Medical Center and Children's Medical Center, Dallas. While the rates of parents who reported that their children harassed others frequently (defined as sometimes, usually or always) decreased from 2003 to 2007, these rates remain high, Dr. Shetgiri said.

Survey results also showed that 23 percent of children had bullied another youngster in 2003 compared to 35 percent in 2007.

Some factors that increase the likelihood that a child will bully others have persisted from 2003 to 2007. For example, children are more likely to be bullies if their parents frequently feel angry with them or feel their child bothers them a lot. In addition, children with an emotional, developmental or behavioral problem and those whose mothers report less than very good mental health also are more likely to be bullies. In fact, about one in five bullies has an emotional, developmental or behavioral problem, more than three times the rate in non-bullies, Dr. Shetgiri noted.

Other factors that seem to protect a child from becoming a bully also have persisted from 2003 to 2007. Parents who share ideas and talk with their child, and who have met most or all of their child's friends are less likely to have children who bully, Dr. Shetgiri said.

"Targeting interventions to decrease these persistent risk factors and increase the persistent protective factors could lead to decreased bullying," she said.

For example, parents can increase involvement with their children by meeting their friends and by spending time talking and sharing ideas with their children, Dr. Shetgiri suggested. "They also can find effective ways to manage any feelings of anger toward their child and can work with health care providers to make sure any emotional or behavioral concerns they have about their child, as well as their own mental health, are addressed."

Source: MedicalXpress.com

 

3D printing technology is a fast and affordable way to build 3D models for neurosurgical planning. Radiologists are able to transform ultra high-resolution CT patient images into 3D solid models using a 3D color printer commonly used in architecture, engineering and construction.

An advantage of 3-D models is that they identify defects that 2-D images do not, which helps radiologists view a clearer impression of the image. With increasing frequency, surgeons and other physicians, and patients alike, request assistance from radiologists in order to identify complex morphologies demonstrated on imaging studies.

"We are applying a technique that has many uses in other industries to aid surgeons in planning procedures on complicated anatomy and pathology as well as help them communicate with patients and their families. Tripler doctors were sending data from Hawaii to the mainland US to have models made at great expense and considerable time. Other radiologists may find these resources in an architect's office or at a factory using 3D printing to make prototypes for just about anything you can fit in a shoebox," said Michelle Yoshida, MD, one of the authors of the exhibit.

Source: ScienceDaily

 

When fully developed as a hand-held, portable sensor, like something you might see in a science fiction movie, it will provide a whole diagnostic laboratory on a single chip.

The research could revolutionize the size, speed and accuracy of chemical detection systems around the world.

New findings on this "microfluidic sensor" were recently reported inSensors and Actuators B: Chemical, a professional journal, and the university is pursuing a patent on related technologies. The collaborative studies were led by Vincent Remcho, an OSU professor of chemistry, and Pallavi Dhagat, an assistant professor in the OSU School of Electrical Engineering and Computer Science.

The key, scientists say, is tapping into the capability of ferromagnetic iron oxide nanoparticles -extraordinarily tiny pieces of rust. The use of such particles in the new system can not only detect chemicals with sensitivity and selectivity, but they can be incorporated into a system of integrated circuits to instantly display the findings.

This diagram illustrates how a new sensor technology developed at Oregon State University might work using magnetic beads. (Credit: Graphic courtesy of Oregon State University)

"The particles we're using are 1,000 times smaller than those now being used in common diagnostic tests, allowing a device to be portable and used in the field," said Remcho, who is also associate dean for research and graduate programs in the OSU College of Science.

"Just as important, however, is that these nanoparticles are made of iron," he said. "Because of that, we can use magnetism and electronics to make them also function as a signaling device, to give us immediate access to the information available."

According to Dhagat, this should result in a powerful sensing technology that is fast, accurate, inexpensive, mass-producible, and small enough to hold in your hand.

"This could completely change the world of chemical assays," Dhagat said.

Existing assays are often cumbersome and time consuming, using biochemical probes that require expensive equipment, expert personnel or a complex laboratory to detect or interpret.

In the new approach, tiny nanoparticles could be attached to these biochemical probes, tagging along to see what they find. When a chemical of interest is detected, a "ferromagnetic resonance" is used to relay the information electronically to a tiny computer and the information immediately displayed to the user. No special thin films or complex processing is required, but the detection capability is still extremely sensitive and accurate.

Essentially, the system might be used to detect almost anything of interest in air or water. And the use of what is ordinary, rusty iron should help address issues of safety in the resulting nanotechnology product.

Rapid detection of chemical toxins used in bioterrorism would be possible, including such concerns as anthrax, ricin or smallpox, where immediate, accurate and highly sensitive tests would be needed. Partly for that reason, the work has been supported by a four-year grant from the Army Research Laboratory, in collaboration with the Oregon Nanoscience and Microtechnologies Institute.

However, routine and improved monitoring of commercial water treatment and supplies could be pursued, along with other needs in environmental monitoring, cargo inspections, biomedical applications in research or medical care, pharmaceutical drug testing, or even more common uses in food safety.

Other OSU researchers working on this project include Tim Marr, a graduate student in electrical engineering, and Esha Chatterjee, a graduate chemistry student.

The concept has been proven in the latest study, scientists say, and work is continuing with microfluidics research to make the technology robust and durable for extended use in the field.

Source: ScienceDaily

 
By Admin (from 01/10/2011 @ 11:00:08, in en - Science and Society, read 1257 times)

Percolating network of rods and spheres. (Credit: Image courtesy of Université du Luxembourg)

Physicists at the University of Luxembourg have developed a new method to improve the electrical conductivity of polymeric composites. Polymeric composites consist of two or more materials and are used for example to shield off electrostatics in airplanes. By introducing additives into polymeric composites, favorable properties can be achieved. For instance, they develop favourable electrical properties when reinforced with carbon nanotubes. Such composites are used to make flat-panel displays and solar cells more efficient.

The researchers in Luxembourg, in cooperation with scientists from the Netherlands, have studied the electrical percolation of carbon nanotubes in a polymer matrix and shown the percolation threshold -- the point at which the polymer composite becomes conductive -- can be considerably lowered if small quantities of a conductive polymer latex are added. The simulations were done in Luxembourg, while the experiments took place at Eindhoven University.

"In this project, the idea is to use as little as possible carbon nanotubes and still benefit from their favourable properties," says the project leader at the University of Luxembourg, Prof. Tania Schilling, "we have discovered that, by adding a second component, we could make use of the resulting interactions to reach our goal." By mixing finely dispersed particles, so-called colloidal particles, of differing shapes and sizes in the medium, system-spanning networks form: the prerequisite for electrically conductive composites.

The recent finding of the materials scientists of the University of Luxembourg was published in the peer-reviewed, scientific journal Nature Nanotechnology. This finding is a result of a cooperation of scientists at the University of Luxembourg, the Technische Universiteit Eindhoven and the Dutch Polymer Institute.

Source: Science Daily

 

In order to realize the full potential of advanced biofuels that are derived from non-food sources of lignocellulosic biomass—e.g., agricultural, forestry, and municipal waste, and crops such as poplar, switchgrass and miscanthus—new technologies that can efficiently and cost-effectively break down this biomass into simple sugars are required. Existing biomass pretreatment technologies are typically derived from the pulp and paper industry and rely on dilute acids and bases to break down the biomass. The treated biomass product is then exposed to biological catalysts, or enzymes, to liberate the sugars.

A new class of solvents, referred to as ionic liquids, have been reported to be much more efficient in treating the biomass and enhancing the yield of sugars liberated from it. While ionic liquids are useful for breaking down biomass, they can also hinder the ability of the cellulases (usually derived from fungi) used to produce sugars after pretreatment. Ionic liquids are a liquid form of salt that will inactivate enzymes by interfering with the folding of polypeptides—the building-blocks of proteins. To help identify new enzymes that are tolerant of ionic liquids, researchers from the U.S. Department of Energy (DOE) Joint Genome Institute (JGI) and the Joint BioEnergy Institute (JBEI) at DOE's Lawrence Berkeley National Laboratory are turning to those found in the complete genome sequences of halophilic (salt-tolerant) organisms.

Salt-loving microbe provides new enzymes for the production of next-gen biofuels

As a test of a bioenergy-related application of DNA sequencing and enzyme discovery, US Department of Energy Joint Genome Institute researchers led by the DOE JGI Director Eddy Rubin, and colleagues from the Joint BioEnergy Institute at DOE's Lawrence Berkeley National Laboratory employed a cellulose-degrading enzyme from a salt-tolerant microbe that was isolated from the Great Salt Lake. Credit: David Gilbert, DOE JGI

As a test of this bioenergy-related application of DNA sequencing and enzyme discovery, researchers led by the Director of the DOE JGI, Eddy Rubin, and the Vice-President of the JBEI Deconstruction Division, Blake Simmons, employed a cellulose-degrading enzyme from a salt-tolerant microbe that was isolated from the Great Salt Lake. The microbe in question, Halorhabdus utahensis, is from the branch of the tree of life known as Archaea; H. utahensis was isolated from the natural environment at the Great Salt Lake and sequenced at the DOE JGI as part of the Genomic Encyclopedia of Bacteria and Archaea (GEBA) project.

"This is one of the only reports of salt-tolerant cellulases, and the only one that represents a true 'genome-to-function' relevant to ionic liquids from a halophilic environment," said Simmons of the study published June 30, 2011 in Green Chemistry. "This strategy enhances the  of identifying true obligatory halophilic enzymes." Such salt-tolerant enzymes, particularly cellulases, offer significant advantages for industrial utility over conventional enzymes.

In collaboration with Jerry Eichler from Ben Gurion University of the Negev in Israel they cloned and expressed a gene from H. utahensis in another haloarchaeal microbe, and were able to identify a salt-dependent enzyme that can tolerate high temperatures and is resistant to ionic liquids. "This project has established a very important link between genomic science and the realization of enzymes that can handle very demanding chemical environments, such as those present in a biorefinery," said Simmons.

The group plans to expand this research to develop a full complement of enzymes that is tailored for the ionic liquid process technology with the goal of demonstrating a complete biomass-to-sugar process, one they hope can enable the commercial viability of advanced biofuels.

Source: PhysOrg

 

University of Illinois engineers have developed a silver-inked rollerball pen capable of writing electrical circuits and interconnects on paper, wood and other surfaces. The pen is writing whole new chapters in low-cost, flexible and disposable electronics.

Led by Jennifer Lewis, the Hans Thurnauer professor of materials science and engineering at the U. of I., and Jennifer Bernhard, a professor of electrical and computer engineering, the team published its work in the journal Advanced Materials.

"Pen-based printing allows one to construct electronic devices 'on-the-fly,' " said Lewis, the director of the Frederick Seitz Materials Research Laboratory at the U. of I. "This is an important step toward enabling desktop manufacturing (or personal fabrication) using very low cost, ubiquitous printing tools."

While it looks like a typical silver-colored rollerball pen, this pen's ink is a solution of real silver. After writing, the liquid in the ink dries to leave conductive silver pathways -- in essence, paper-mounted wires. The ink maintains its conductivity through multiple bends and folds of the paper, enabling devices with great flexibility and conformability.

Metallic inks have been used in approaches using inkjet printers to fabricate electronic devices, but the pen offers freedom and flexibility to apply ink directly to paper or other rough surfaces instantly, at low cost and without programming.

"The key advantage of the pen is that the costly printers and printheads typically required for inkjet or other printing approaches are replaced with an inexpensive, hand-held writing tool," said Lewis, who is also affiliated with the Beckman Institute for Advanced Science and Technology.

The ability to create freestyle conductive pathways enables new possibilities in art, disposable electronics and folded three-dimensional devices. For example, the researchers used the silver pen to sketch a copy of the painting "Sae-Han-Do" by Jung Hee Kim, which portrays a house, trees and Chinese text. The ink serves as wiring for an LED mounted on the roof of the house, powered by a five-volt battery connected to the edge of the painting. The researchers also have demonstrated a flexible LED display on paper, conductive text and three-dimensional radio-frequency antennas.

Next, the researchers plan to expand the palette of inks to enable pen-on-paper writing of other electronic and ionically conductive materials.

The U.S. Department of Energy supported this work. Co-authors were graduate student Analisa Russo and postdoctoral researchers Bok Yeop Ahn, Jacob Adams and Eric Duoss.

Source: ScienceDaily

 

IBM researchers have developed a programming trick that makes it possible to more reliably store large amounts of data using a promising new technology called phase-change memory. The company hopes to start integrating this storage technology into commercial products, such as servers that process data for the cloud, in about five years.

Like flash memory, commonly found in cell phones, phase-change memory is nonvolatile. That means it doesn't require any power to store the data. And it can be accessed rapidly for fast boot-ups in computers and more efficient operation in general. Phase-change memory has a speed advantage over flash, and Micron and Samsung are about to bring out products that will compete with flash in some mobile applications.

Long-term memory: Each cell in this 200,000-cell phase-change memory chip can store multiple bits of data reliably over a period of several months.

These initial products will use memory cells that store one bit each. But for phase-change memory to be cost-competitive for broader applications, it will need to achieve higher density, storing multiple bits per cell. Greater density is necessary for IBM to achieve its goal of developing phase-change memory for high-performance systems such as servers that process and store Internet data much faster.

The IBM work announced today offers a solution. In the past, researchers haven't been able to make a device that uses multiple bits per cell that works reliably over months and years. That's because of the properties of the phase-change materials used to store the data. Scientists at IBM Research in Zurich have developed a software trick that allows them to compensate for this.

Each cell in these data-storage arrays is made up of a small spot of phase-change materials sandwiched between two electrodes. By applying a voltage across the electrodes, the material can be switched to any number of states along a continuum from totally unstructured to highly crystalline. The memory is read out by using another electrical pulse to measure the resistance of the material, which is much lower in the crystalline state.

To make multibit memory cells, the IBM group picked four different levels of electrical resistance. The trouble is that over time, the electrons in the phase-change cells tend to drift around, and the resistance changes, corrupting the data. The IBM group has shown that they can encode the data in such a way that when it's read out, they can correct for drift-based errors and get the right data.

The IBM group has shown that error-correcting code can be used to reliably read out data from a 200,000-cell phase-change memory array after a period of six months. "That's not gigabits, like flash, but it's impressive," says Eric Pop, professor of electrical engineering and computer sciences at the University of Illinois at Urbana-Champaign. "They're using a clever encoding scheme that seems to prolong the life and reliability of phase-change memory."

For commercial products, that reliability timescale needs to come up to 10 years, says Victor Zhirnov, director of special projects at the Semiconductor Research Corporation. IBM says it can get there. "Electrical drift in these materials is mostly problematic in the first microseconds and minutes after programming," says Harris Pozidis, manager of memory and probe technologies at IBM Research in Zurich. The problem of drift can be statistically accounted for in the IBM coding scheme over whatever timeframe is necessary, says Pozidis, because it occurs at a known rate.

But phase-change memory won't be broadly adapted until power consumption can be checked, says Zhirnov. It still takes much too much energy to flip the bits in these arrays. That's due to the way the electrodes are designed, and many researchers are working on the problem. This spring, Pop's group at the University of Illinois demonstrated storage arrays that use carbon nanotubes to encode phase-change memory cells with 100 times less power.

Source: Technology Review

 
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Hi, it's Nathan!Pretty much everyone is using voice search with their Siri/Google/Alexa to ask for services and products now, and next year, it'll be EVERYONE of your customers. Imagine what you are ...
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Now Colorado is one love, I'm already packing suitcases;)
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