Geneva – Particle beams are once again circulating in the world’s most powerful particle accelerator, CERN¹’s Large Hadron Collider (LHC). This news comes after the machine was handed over for operation on Wednesday morning. A clockwise circulating beam was established at ten o’clock this evening. This is an important milestone on the road towards first physics at the LHC, expected in 2010.

(CERN)

“It’s great to see beam circulating in the LHC again,” said CERN Director General Rolf Heuer. “We’ve still got some way to go before physics can begin, but with this milestone we’re well on the way.”

The LHC circulated its first beams on 10 September 2008, but suffered a serious malfunction nine days later. A failure in an electrical connection led to serious damage, and CERN has spent over a year repairing and consolidating the machine to ensure that such an incident cannot happen again.

“The LHC is a far better understood machine than it was a year ago,” said CERN’s Director for Accelerators, Steve Myers. “We’ve learned from our experience, and engineered the technology that allows us to move on. That’s how progress is made.”

Recommissioning the LHC began in the summer, and successive milestones have regularly been passed since then. The LHC reached its operating temperature of 1.9 Kelvin, or about -271 Celsius, on 8 October. Particles were injected on 23 October, but not circulated. A beam was steered through three octants of the machine on 7 November, and circulating beams have now been re-established. The next important milestone will be low-energy collisions, expected in about a week from now. These will give the experimental collaborations their first collision data, enabling important calibration work to be carried out. This is significant, since up to now, all the data they have recorded comes from cosmic rays. Ramping the beams to high energy will follow in preparation for collisions at 7 TeV (3.5 TeV per beam) next year.

Particle physics is a global endeavour, and CERN has received support from around the world in getting the LHC up and running again.

“It’s been a herculean effort to get to where we are today,” said Myers. “I’d like to thank all those who have taken part, from CERN and from our partner institutions around the world.”

^1. CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

- CERN, the European Organization for Nuclear Research -

Aliens are stealing your beloved sheep and you’ve got to stop them. That’s the premise for TowerMadness, a new 3D iPhone game that is one of the most cheat-resistant iPhone games available, according to its three developers, all with ties to the University of California, San Diego.

Screen shot from TowerMadness, a 3D iPhone game created by UC San Diego computer science students, past and present. (University of California, San Diego)

Three current and former UC San Diego computer science students created TowerMadness, the cheat-resistant 3D game which challenges players to repel alien onslaughts by constructing defensive towers in strategic locations. A multi-touch interface allows TowerMadness players to zoom in and around the visually-detailed 3D action.

The game’s cheat resistance is rooted in a unique online replay feature. In particular, the developers built a proprietary replay verification system that automatically replays high-scoring games and checks that players legitimately scored as many points as their devices are reporting.

“The replays allow us to verify that the games submitted to our servers are genuine, keeping the online global scoring fair and fun for everyone,” said Iman Mostafavi, a computer science Ph.D. student at the UC San Diego Jacobs School of Engineering and one of the game’s three developers.

Each replay is a tamper-resistant, highly compact recording of a player’s actions over the course of a game.

“We’ve already thwarted several attempts at cheating,” said co-developer Volker Schönefeld, a former visiting graduate student to UC San Diego’s computer science department who is completing his doctoral degree at RWTH Aachen University, in Aachen Germany.

The replays are significantly smaller than a video of the same length and can be transmitted over the Internet in seconds.

TowerMadness’ replay features grew out of the technology Schönefeld pioneered in 2003 for Waaagh!TV, his e-Sports broadcasting company. Waaagh!TV develops software that allows thousands of users to simultaneously watch live online matches of the popular computer game Warcraft III.

In addition to cheat resistance, the replay feature allows TowerMadness players to show off their strategies and learn new ones by watching completed games. Anyone with a copy of TowerMadness can watch the replays.

The game includes additional online features supported by Google’s App Engine cloud computing platform. Players can compete globally for high scores, download free additional game content, and share their games on Twitter and Facebook.

Schönefeld and Mostafavi, along with Arash Keshmirian, a UC San Diego computer science BS/MS alumnus, began developing TowerMadness in their spare time shortly after Schönefeld’s first visit to the department in 2008. “With our shared interest in building apps for the platform, combined with many years of experience in developing computer graphics software, I knew we could push the iPhone’s capabilities to a level where only experienced developers could compete. This would be an important differentiator in an already crowded marketplace,” said Keshmirian, who is now an entrepreneur and consultant based in Silicon Valley.

On May 15, 2009, after nearly six months of development, TowerMadness scored a preview feature on the holy grail of iPhone gaming Touch Arcade, which fueled widespread anticipation for the release. The game went live on May 23rd, and news and reviews of the game began appearing on numerous blogs, web sites, and media around the world. Several days later, TowerMadness won an award from the prominent mobile gaming web site Pocket Gamer.

Another big visibility boost came when Apple picked TowerMadness for a prized high-profile spot on the iTunes App Store itself—the Featured Apps section.

“In a sea of over 50,000 apps, visibility is paramount. Being put in the spotlight by Apple early on has been a tremendous boon,” according to the developers. Only a month since its launch, players have submitted well over 150,000 rounds of TowerMadness to the online leaderboards.

Much of the cutting-edge 3D graphics, programming and gaming know-how that is helping to make TowerMadness popular was developed, strengthened or nurtured at UC San Diego. The UCSD Department of Computer Science and Engineering (CSE) and the UC San Diego Division of Calit2 (California Institute of Telecommunications and Information Technology) played particularly important roles.

The trio’s company, Limbic Software, plans to continue releasing downloadable content and updates for TowerMadness. Hoping to bring the excitement of competitive gaming to mobile gamers, the game will soon allow players to compete for real prizes. The team is also working hard towards the release of their upcoming second game.

The TowerMadness web site http://www.towermadness.com features more information, screenshots, and videos.

Before developing TowerMadness, Iman Mostafavi worked on various visualization projects at Calit2, including some that matured into StarCAVE, a five-sided virtual reality room where scientific models and animations are projected in stereo on 360-degree screens surrounding the viewer, and onto the floor.

Mostafavi also develops algorithms for improving the quality and utility of 3D models that represent biological data gleaned from biological images taken by electron microscopes. Mostafavi performs this work at the National Center for Microscopy and Imaging Research (NCMIR) at UC San Diego, which develops state-of-the-art 3D imaging and analysis technologies to help biomedical researchers understand biological structure and function relationships in cells and tissues.

Mostafavi also collaborated on UC San Diego interactive artwork, shown at SIGGRAPH 2007, that explored new ways of representing nature in the era of metagenomics.

At UC San Diego, Keshmirian developed physically-based simulations of light transport to produce realistic images of various phenomena, such as light passing through plant leaves. Keshmirian’s 2008 thesis, with advisor, computer science professor Henrik Wan Jensen, describes a new, and significantly more complete model for the simulation of light within camera lenses. The techniques can be used to artificially produce many of the effects observed when taking photographic pictures in the real world, thereby enhancing simulated images. Keshmirian was also the editor of the photography department at the UCSD Guardian, the university’s official student-run newspaper.

“Having the opportunity to take two completely different perspectives on photography: scientific and artistic, was a real boon for both my research and my art,” remarks Keshmirian. Keshmirian’s creative eye helped him develop the quirky-cute visual style for TowerMadness.

During his six month stay at the computer science department at UC San Diego, Schönefeld worked on his Master’s thesis, the topic of which is the mathematical analysis of physically-based simulation of light as it travels through a virtual scene. Schönefeld performed this research under the supervision of computer science professor Henrik Wann Jensen.

TowerMadness Gameplay: Tutorial and Easy Map

By Daniel Kane – University of California, San Diego

New type of resin for exact replicates of bone and heart valves

Biodegradable carrier structure made using stereolithography. The newly-developed polylactide-based resin makes it possible to replicate three-dimensional digital structures very accurately. The white bar is 500 micrometre in length. A) photograph of a porous structure fabricated using stereolithography. B) Micro-CT scan of the structure fabricated. C) Electron microscope image. D) Porous structure sown with bone cells. (Universiteit Twente)

Researchers at the University of Twente (UT) have developed a new type of resin that can be broken down by the body. This new resin makes it possible to replicate important body parts exactly and make them fit precisely. The resin can be given different properties depending on where in the body it is to be used. Cells can be sown and cultured on these models, so that the tissues grown are, in fact, produced by the body itself. The new resin has been developed by Ferry Melchels and Prof. Dirk Grijpma of the UT’s Polymer Chemistry and Biomaterials research group. An article on this breakthrough will be appearing in the authoritative specialist journal, Biomaterials.

Stereolithography is a technology with which three-dimensional objects can be made from a digital design. It is also possible to scan an object using a CT scanner (or micro-CT scanner) to obtain a digital image. The object in question can subsequently be copied extremely accurately with a stereolithograph. A stereolithograph is therefore a 3D replicating machine with a very high resolution. The way it works is based on the local hardening of a liquid resin with computer-driven light. The resins available for stereolithography so far harden into chemical networks that cannot be broken down.

Resin
For the first time, researchers from the UT have developed a biodegradable resin that can be used for this replicating machine. They have made the resin in such a way that it can be broken down by the body. Making objects from this resin may have great advantages for a many medical applications. If, for example, a child has a heart valve disorder, a 3D digital image of the heart valve can be created using a CT scanner. The model in the stereolithograph can be copied exactly with the new resin. If the structure is made porous, the child’s own cells can be placed on it. This porosity also gives nutrients access to the cells. Ultimately, after the carrier structure has broken down, only the natural tissue remains. Another possibility is to use the resin to create structures for correcting skull defects. You can fabricate a shape very accurately using a stereolithograph. By growing the patient’s own cells on it, his or her own natural bone tissue will be regenerated.

Properties
The properties of the hardened resin must be variable as very different characteristics are needed for soft tissues than for harder ones, such as bone. Mechanical behaviour, cell adhesion, moisture absorbing capacity and degradability are important properties. Bone material, for example, must be rigid and calcium salts must be able to precipitate on it, whilst these characteristics are not desirable in the case of soft tissues.

Universiteit Twente

Traditional cell phones have been immune to viruses because they lack standardized operating systems. However, as smart phones rapidly increase in market share, viruses pose a serious threat to mobile communications.

Photographer: Dorothea Jacob www.pixelio.de

A new study in the journal Science that is coauthored by University of Notre Dame physics doctoral student Pu Wang and researchers from Northeastern University suggests that the risk of mobile phone virus attacks will increase as a few operating systems gain more market share. The study also analyzes the pattern and speed of the spread of infection for Bluetooth and multimedia messaging services (MMS). The researchers used anonymous billing records of 6.2 million mobile subscribers and tracked calling patterns using the location of the closest mobile phone tower.

Smart phones, which can share programs and data, could attract virus writers at a level more disruptive than computer viruses. Mobile viruses can be spread by either Bluetooth or MMS communications protocols. Bluetooth viruses can infect phones with the technology within a local area, comparable to the spread of contact-based disease. The infected phone must be moved into another tower’s range in order to infect a new set of phones. The slow spread provides time to develop protection from the virus.

MMS viruses, like computer viruses, can send copies to everyone in the infected phone’s address book and copy themselves into a new handset in about two minutes, but the underlying call network is so fragmented that viruses can access only a fraction of susceptible phones. Since 2005, virus writers have developed hybrids that spread with both Bluetooth and MMS connections.

Wang, who is part of Notre Dame’s Center for Complex Network Research, notes that the increasing dominance of some operating systems for smart phones leaves the technology vulnerable to attacks by sophisticated virus writers.

“We believe that the understanding of the basic spreading patterns presented here could help estimate the realistic risks carried by mobile phone viruses and aid in the development of proper measures so as to avoid the costly impact of future outbreaks,” he said.

The other authors of the study are Marta C. González and Albert-László Barabási of the Center for Complex Network Research at Northeastern University.

Researchers at the University of Chicago and Lawrence Berkeley National Laboratory have developed an “electronic glue” that could accelerate advances in semiconductor-based technologies, including solar cells and thermoelectric devices that convert sun light and waste heat, respectively, into useful electrical energy.

A vial of nanocrystals in solution, which serve as “electronic glue” for semiconductor-based technologies. (Dan Dry)

Semiconductors have served as choice materials for many electronic and optical devices because of their physical properties. Commercial solar cells, computer chips and other semiconductor technologies typically use large semiconductor crystals. But that is expensive and can make large-scale applications such as rooftop solar-energy collectors prohibitive.

For those uses, engineers see great potential in semiconductor nanocrystals, sometimes just a few hundred atoms each. Nanocrystals can be readily mass-produced and used for device manufacturing via inkjet printing and other solution-based processes. But a problem remains: The crystals are unable to efficiently transfer their electric charges to one another due to surface ligands—bulky, insulating organic molecules that cap nanocrystals.

The “electronic glue” developed in Dmitri Talapin’s laboratory at the University of Chicago solves the ligand problem. The team describes in the journal Science how substituting the insulating organic molecules with novel inorganic molecules dramatically increases the electronic coupling between nanocrystals. The University of Chicago licensed the underlying technology for thermoelectric applications to Evident Technologies in February.

Citation: “Colloidal Nanocrystals with Molecular Metal Chalcogenide Surface Ligands,” Maksym V. Kovalendo, Department of Chemistry, University of Chicago; Marcus Scheele, Molecular Foundry, Lawrence Berkeley National Laboratory; and Dmitri V. Talapin, Department of Chemistry, University of Chicago, and Center for Nanoscale Materials, Argonne National Laboratory, Science, June 12, 2009.

Funding sources: American Chemical Society Petroleum Research Fund, the Chicago Energy Initiative, U.S. Department of Energy and Evident Technologies Inc.

The University of Chicago

New research shows abrupt climate change over 14,000 years ago associated with a shift in monsoon patterns and a decline vegetation growth.

Oxygen gas in ice cores has shown evidence for abrupt climate change.Credit: Zina Deretsky, National Science Foundation

When the climate warmed relatively quickly about 14,700 years ago, seasonal monsoons moved southward, dropping more rain on the Earth’s oceans at the expense of tropical areas, according to climate researchers. If the same pattern occurs in the coming decades as the Earth’s temperatures rises due to climate change, the highly-populated regions of the world that depend on monsoons could face more wildfires, water shortages and lower agricultural production.

In an article to be published in the June 12 issue of the journal Science, researchers from the Desert Research Institute in Nevada, the Scripps Institution of Oceanography and Oregon State University present their findings after comparing oxygen isotopes in air that was captured in ice cores and previously published data from ancient stalagmites found in caves. The research was supported by the National Science Foundation.

The ice cores, gathered from different locations in Antarctica and Greenland, contain air bubbles that were trapped as the ice formed over tens of thousands of years. By measuring the amount of certain oxygen isotopes in those air bubbles, the researchers were able to determine patterns in vegetation growth worldwide over that same span of time.

The researchers found that beginning about 14,700 years ago, the mixture of oxygen isotopes began to change in a way that suggests less vegetation growth, and this process continued for at least 200 years. The researchers then compared these findings with data from an earlier study that determined the amount of rainfall that fell in China over many millennia by examining stalagmites in caves. They discovered that this period of low vegetation growth corresponded with a time of reduced monsoon rainfall.

By climate standards, the researchers say, this shift happened abruptly over a few decades. They also caution that observations of past climate events may not be able predict future conditions. Given the vital roll that monsoons play in sustaining billions of people, however, this connection between climate change and monsoon patterns may be an ominous sign of what climate change in the 21^st century may bring.

The National Science Foundation

AUGUSTA, Ga. – The Nintendo Wii may help treat symptoms of Parkinson’s disease, including depression, a Medical College of Georgia researcher says.

Parkinson’s disease is a degenerative disease that impairs motor skills. Dr. Herz theorized that the popular computer game console, which simulates various sports and activities, could improve coordination, reflexes and other movement-related skills, but he found additional benefits as well.

“The Wii allows patients to work in a virtual environment that’s safe, fun and motivational,” says Dr. Ben Herz, program director and assistant professor in the School of Allied Health Sciences Department of Occupational Therapy. “The games require visual perception, eye-hand coordination, figure-ground relationships and sequenced movement, so it’s a huge treatment tool from an occupational therapy perspective.”

In an eight-week pilot study, 20 Parkinson’s patients spent an hour playing the Wii three times a week for four weeks. The patients, all in a stage of the disease in which both body sides are affected but with no significant gait disturbance yet, played two games each of tennis and bowling and one game of boxing—games entailing exercise, bilateral movement, balance and fast pace.

“By the middle of the study, we actually had a number of people who could [defeat] their opponent out in the first round, which amazed us,” says Dr. Herz, who presented his preliminary findings at the fifth annual Games for Health Conference today in Boston.

The victories weren’t the biggest surprise, however. Participants showed significant improvements in rigidity, movement, fine motor skills and energy levels. Perhaps most impressively, most participants’ depression levels decreased to zero.

An estimated 45 percent of Parkinson’s patients are reported to suffer from depression, though Dr. Herz suspects the actual figure is much higher.

Studies have shown that exercise and video games independently can increase the production of dopamine, a neurotransmitter deficient in Parkinson’s patients. He suspects that’s the case with the Wii’s exercise effect. Dopamine also helps improve voluntary, functional movements, which Parkinson’s patients “use or lose,” Dr. Herz says.

Wii, which features simulated movements such as cracking an egg, swinging a tennis racket and throwing a bowling ball, responds to a player’s movements rather than cues from a controller, so players can do full body movements and see their progress on a screen.

“I think we’re going to be using virtual reality and games a lot more because it provides a controlled physical environment that allows patients to participate in the activities they need or want to do. A patient doesn’t have to go to a bowling alley and worry about environmental problems or distractions,” Dr. Herz says.

Dr. Herz’s research was funded by a $45,000 grant from the National Parkinson’s Foundation. Next he plans to test the Wii Fit balance board with Parkinson’s patients and expand his studies to multiple sites.

“Game systems are the future of rehab,” Dr. Herz says. “About 60 percent of the study participants decided to buy a Wii for themselves. That speaks volumes for how this made them feel.”

By Paula Hinely – Medical College of Georgia

Solar electricity has a future: It is renewable and available in unlimited quantities, and it does not produce any gases detrimental to the climate. Its only drawback right now is the price: the electric power currently being produced by solar cells in northern Europe must be subsidized if it is to compete against the household electricity generated by traditional power plants. At “Laser 2009″ in Munich, June 15 to 18, Fraunhofer researchers will be demonstrating how laser technology can contribute to optimizing the manufacturing costs and efficiency of solar cells.

The laser beam is guided and focused by means of a process adapted manufacturing system. This allows thousands of holes to be burned into a silicon wafer in one second. Credit: Fraunhofer ILT

Cell phones, computers, MP3 players, kitchen stoves, and irons all have one thing in common: They need electricity. And in the future, more and more cars will also be fuelled by electric power. If the latest forecast from the World Energy Council WEC can be believed, global electricity requirements will double in the next 40 years. At the same time, prices for the dwindling resources of petroleum and natural gas are climbing.

“Rising energy prices are making alternative energy sources increasingly cost-effective. Sometime in the coming years, renewable energy sources, such as solar energy, will be competitive, even without subsidization,” explains Dr. Arnold Gillner, head of the microtechnology department at the Fraunhofer Institute for Laser Technology in Aachen, Germany. “Experts predict that grid parity will be achieved in a few years. This means that the costs and opportunities in the grid will be equal for solar electricity and conventionally generated household electricity.” Together with his team at the Fraunhofer Institute for Laser Technology ILT in Aachen, this researcher is developing technologies now that will allow faster, better, and cheaper production of solar cells in the future. “Lasers work quickly, precisely, and without contact. In other words, they are an ideal tool for manufacturing fragile solar cells. In fact, lasers are already being used in production today, but there is still considerable room for process optimization.” In addition to gradually improving the manufacturing technology, the physicists and engineers in Aachen are working with solar cell developers – for example, at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg – on new engineering and design alternatives.

New production technologies allow new design alternatives

At “Laser 2009” in Munich, the researchers will be demonstrating how lasers can drill holes into silicon cells at breathtaking speed: The ILT laser system drills more than 3,000 holes within one second. Because it is not possible to move the laser source at this speed, the experts have developed optimized manufacturing systems which guide and focuses the light beam at the required points. “We are currently experimenting with various laser sources and optical systems,” Gillner explains. “Our goal is to increase the performance to 10,000 holes a second. This is the speed that must be reached in order to drill 10,000 to 20,000 holes into a wafer within the cycle time of the production machines.”

The tiny holes in the wafer – their diameter is only 50 micrometers – open up undreamt-of possibilities for the solar cell developers.  “Previously, the electrical contacts were arranged on the top of the cells. The holes make it possible to move the contacts to the back, with the advantage that the electrodes, which currently act as a dark grid to absorb light, disappear. And so the energy yield increases. The goal is a degree of efficiency of 20 percent% in industrially-produced emitter wrap-through (EWT) cells, with a yield of one-third more than classic silicon cells,” Gillner explains. The design principle itself remains unchanged: In the semi-conductor layer, light particles, or photons, produce negative electrons and positive holes, each of which then wanders to the oppositely poled electrodes. The contacts for anodes and cathodes in the EWT cells are all on the back, there is no shading caused by the electrodes, and the degree of efficiency increases. With this technique, it may one day be possible to use unpurified “dirty” silicon to manufacture solar cells that have poorer electrical properties, but that are cheaper.

Drilling holes into silicon cells is only one of many laser applications in solar cell manufacturing. In the EU project Solasys – Next Generation Solar Cell and Module Laser Processing Systems – an international research team is currently developing new technologies that will allow production to be optimized in the future. ILT in Aachen is coordinating the six million euro project. “We are working on new methods that make the doping of semiconductors, the drilling and the surface structuring of silicon, the edge isolation of the cells, and the soldering of the modules more economical,” project coordinator Gillner explains. For example, “selective laser soldering” makes it possible to improve the rejection rates and quality of the contacting, and so reduce manufacturing costs. Until now, the electrodes were mechanically pressed onto the cells, and then heated in an oven. “But silicon cells often break during this process,” Gillner knows. “Breakage is a primary cost factor in production.” On the other hand, however, with “selective laser soldering” the contacts are pressed on to the cells with compressed air and then soldered with the laser. The mechanical stress approaches zero and the temperature can be precisely regulated. The result: Optimal contacts and almost no rejects.

Laser technology means more efficient thin film cells

Laser technology is also helping to optimize the manufacture of thin film solar cells. The extremely thin film packages made of semiconducting oxide, amorphous silicon, and metal that are deposited onto the glass panels still have a market share of only ten percent. But as Gillner knows, “This could be higher, because thin film solar cells can be used anywhere that non-transparent glass panels can be mounted, for example, on house facades or sound-insulating walls. But the degrees of efficiency are comparable low at five to eight percent, and the production costs are comparatively high.” The laser researchers are working to improve these costs. Until now, the manufacturers have used mechanical methods or solid-state lasers in the nanosecond range in order to structure the active layers on the glass panels. In order to produce electric connections between the semiconductor and the metal, grooves only a few micrometers wide must be created. At the Fraunhofer-Gesellschaft booth at “Laser 2009” the ILT researchers will be demonstrating a 400-watt ultrashort pulse laser that processes thin-film solar modules ten times faster than conventional diode-pumped solid-state lasers. “The ultrashort pulse laser is an ideal tool for ablating thin layers: It works very precisely, does not heat the material and, working with a pulse frequency of 80 MHz, can process a 2-by-3 meter glass panel in under two minutes,” Gillner reports. “The technology is still very new, and high-performance scanning systems and optical systems adapted to the process must be developed first. In the medium term, however, this technology will be able to reduce production costs.”

The rise of laser technology in solar technology is just taking off, and it still has a long way to go. “Lasers simplify and optimize the manufacture of classic silicon and thin-film cells, and they allow the development of new design alternatives,” Gillner continues. “And so laser technology is making an important contribution towards allowing renewable energy sources to penetrate further into the energy market.”

Fraunhofer-Gesellschaft

PHILADELPHIA –- Engineers from the University of Pennsylvania, Sandia National Laboratories and Rice University have demonstrated the formation of interconnected carbon nanostructures on graphene substrate in a simple assembly process that involves heating few-layer graphene sheets to sublimation using electric current that may eventually lead to a new paradigm for building integrated carbon-based devices.

An electron micrograph showing the formation of interconnected carbon nanostructures on a graphene substrate, which may be harnessed to make future electronic devices.

Curvy nanostructures such as carbon nanotubes and fullerenes have extraordinary properties but are extremely challenging to pick up, handle and assemble into devices after synthesis. Penn materials scientist Ju Li and Sandia scientist Jianyu Huang have come up with a novel idea to construct curvy nanostructures directly integrated on graphene, taking advantage of the fact that graphene, an atomically thin two-dimensional sheet, bends easily after open edges have been cut on it, which can then fuse with other open edges permanently, like a plumber connecting metal fittings.

The “knife” and “welding torch” used in the experiments, which were performed inside an electron microscope, was electrical current from a Nanofactory scanning probe, generating up to 2000°C of heat. Upon applying the electrical current to few-layer graphene, they observed the in situ creation of many interconnected, curved carbon nanostructures, such as “fractional nanotube”-like graphene bi-layer edges, or BLEs; BLE rings on graphene equivalent to “anti quantum-dots”; and nanotube-BLE assembly connecting multiple layers of graphene.

Remarkably, researchers observed that more than 99 percent of the graphene edges formed during sublimation were curved BLEs rather than flat monolayer edges, indicating that BLEs are the stable edges in graphene, in agreement with predictions based on symmetry considerations and energetic calculations. Theory also predicts these BLEs, or “fractional nanotubes,” possess novel properties of their own and may find applications in devices.

The study is published in the current issue of the journal Proceedings of the National Academy of Sciences. Short movies of the fabrication of these nanostructures can be viewed at www.youtube.com/user/MaterialsTheory.
Li and Huang observed the creation of these interconnected carbon nanostructures using the heat of electric current and a high-resolution transmission electron microscope. The current, once passed through the graphene layers, improved the crystalline quality and surface cleanness of the graphene as well, both important for device fabrication.

The sublimation of few-layer graphene, such as a 10-layer stack, is advantageous over the sublimation of monolayers. In few-layer graphene, layers spontaneously fuse together forming nanostructures on top of one or two electrically conductive, extended, graphene sheets.

During heating, both the flat graphene sheets and the self-wrapping nanostructures that form, like bilayer edges and nanotubes, have unique electronic properties important for device applications. The biggest obstacle for engineers has been wrestling control of the structure and assembly of these nanostructures to best exploit the properties of carbon. The discoveries of self-assembled novel carbon nanostructures may circumvent the hurdle and lead to new approach of graphene-based electronic devices.

Researchers induced the sublimation of multilayer graphene by Joule-heating, making it thermodynamically favorable for the carbon atoms at the edge of the material to escape into the gas phase, leaving freshly exposed edges on the solid graphene. The remaining graphene edges curl and often welded together to form BLEs. Researchers attribute this behavior to nature’s driving force to reduce capillary energy, dangling bonds on the open edges of monolayer graphene, at the cost of increased bending energy.

“This study demonstrates it is possible to make and integrate curved nanostructures directly on flat graphene, which is extended and electrically conducting,” said Li, associate professor in the Department of Materials Science and Engineering in Penn’s School of Engineering and Applied Science. “Furthermore, it demonstrates that multiple graphene sheets can be intentionally interconnected. And the quality of the plumbing is exceptionally high, better than anything people have used for electrical contacts with carbon nanotubes so far. We are currently investigating the fundamental properties of graphene bi-layer edges, BLE rings and nanotube-BLE junctions.”

The study was performed by Li and Liang Qi of Penn, Jian Yu Huang and Ping Lu of the Center for Integrated Nanotechnologies at Sandia and Feng Ding and Boris I. Yakobson of the Department of Mechanical Engineering and Materials Science at Rice.

It was supported by the National Science Foundation, the Air Force Office of Scientific Research, the Honda Research Institute, the Department of Energy and the Office of Naval Research.

Sleep disturbances increase as we age. Some studies report more than half of seniors 65 years of age or older suffer from chronic sleep disturbances. Researchers have long believed that the sleep disturbances common among the elderly often result from a disruption of the body’s circadian rhythms — biological cycles that repeat approximately every 24 hours.

(source: Lighting Research Center)

In recent years, scientists at Rensselaer Polytechnic Institute’s Lighting Research Center and elsewhere have demonstrated that blue light is the most effective at stimulating the circadian system when combined with the appropriate light intensity, spatial distribution, timing, and duration. A team at the Lighting Research Center (LRC) has tested a goggle-like device designed to deliver blue light directly to the eyes to improve sleep quality in older adults.

“Light and dark patterns are the major synchronizer of circadian rhythms to the 24-hour solar day,” said Mariana Figueiro, Ph.D., Lighting Research Center Light and Health Program director and principal investigator on the project.  “Light stimulus travels through the retina, the light-sensitive nerve tissue lining the back wall of the eye, to reach the master clock in the brain. However, a combination of age-related changes in the eye and a more sedentary lifestyle may reduce the amount of light stimulus reaching an older person’s retina, therefore reducing the amount of light for the circadian system.”

As we age, the lens in the eye thickens and the pupil shrinks, reducing the amount of light passing through to the retina.  Making matters worse, in some cases, such as with persons with Alzheimer’s disease, the circadian system may require a stronger light stimulus due to deteriorating neural processes in the brain.  These physical and neural changes can lead to muted signals to the circadian system. Factor in environmental influences, such as an indoor lifestyle with less access to daylight, and you have a perfect scenario for the development of irregular sleep-activity patterns, according to Figueiro.

The research team explains that a marked increase in daytime lighting levels can counteract the age-dependent losses in retinal light exposure by providing a stronger signal to the circadian system.  However, the color and intensity of commercially available lighting systems, like those used in senior residences, assisted-living facilities, and nursing homes, are designed for visual effectiveness and minimal energy use and not necessarily efficacious for generating light to stimulate the older circadian system.

Commercially-available “white” light sources advertised to treat circadian-related sleep disorders are usually very bright light and can cause glare and compromise compliance.

In this project, the light-treatment prototype tested by Figueiro’s team was developed by Topbulb.com, LLC, based on prior LRC light and health research. The device offers an alternative approach using specially designed goggles that deliver blue light spectrally tuned for optimum circadian response.

“The goal of this phase of the development project was to create a device in a smaller form factor or envelope that allowed for social inclusion and end-user mobility, while still delivering the required dose of light,” said Topbulb.com Senior Developer Philip H. Bonello, Ph.D.

The device was worn by eleven subjects between the ages of 51 and 80 years of age. Each subject was exposed to two levels of blue light (about 50 lux and 10 lux) from the personal light-treatment device for 90 minutes on two separate nights.  Blood and saliva samples were collected at prescribed times to assess levels of nocturnal melatonin, a hormone used as a marker for the circadian clock, with high levels at night when a person is in a dark environment and low levels during the day.

After only one hour of light exposure, the light-induced nocturnal melatonin suppression level was about 35 percent for the low light level and about 60 percent for the high light level. In addition, the higher level of blue light suppressed nocturnal melatonin more quickly, to a greater extent over the course of the 90-minute exposure period, and was maintained after 60 minutes.

Having demonstrated its stimulation effect on the circadian system, the researchers believe the device could be subsequently used to increase sleep consolidation and efficiency in older subjects when worn for a prescribed duration at an appropriate time.

“The study suggests that the light goggles might be a practical, comfortable, and effective way to deliver light treatment to those suffering from circadian sleep disorders. The next steps are to conduct field studies where we will be testing the effectiveness of this personal light-treatment device on those suffering from circadian-related sleep disorders, while also  verifying the acceptance of the a device among the test groups,” said Figueiro.

Figueiro carried out her research with LRC scientists Andrew Bierman, John Bullough, Ph.D., and Mark Rea, Ph.D.  They co-authored a paper detailing the study, “A Personal Light-Treatment Device for Improving Sleep Quality in the Elderly: Dynamics of Nocturnal Melatonin Suppression at Two Exposure Levels,” which was recently published in Chronobiology International, Volume 26 Issue 4, 726.

This study was supported by the National Institute on Aging (1R41AG029693) through a Small Business Technology Transfer grant to Topbulb.com, LLC, a commercial and residential resource for light bulbs.

Rensselaer Polytechnic Institute (RPI)