Science

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Researchers Report Novel Approach for Single Molecule Electronic DNA Sequencing

DNA sequencing is the driving force behind key discoveries in medicine and biology. For instance, the complete sequence of an individual's genome provides important markers and guidelines for medical diagnostics and healthcare. Up to now, the major roadblock has been the cost and speed of obtaining highly accurate DNA sequences. While numerous advances have been made in the last 10 years, most current high-throughput sequencing instruments depend on optical techniques for the detection of the four building blocks of DNA: A, C, G and T. To further advance the measurement capability, electronic DNA sequencing of an ensemble of DNA templates has also been developed. Recently, it has been shown that DNA can be threaded through protein nanoscale pores under an applied electric current to produce electronic signals at single molecule level. However, because the four nucleotides are very similar in their chemical structures, they cannot easily be distinguished using this technique. Thus, the research and development of a single-molecule electronic DNA sequencing platform is the most active area of investigation and has the potential to produce a hand-held DNA sequencer capable of deciphering the genome for personalized medicine and basic biomedical research.

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Schematic of single molecule DNA sequencing by a nanopore with phosphate-tagged nucleotides. Each of the four nucleotides will carry a different tag. During SBS, these tags, attached via the terminal-phosphate of the nucleotide, will be released into the nanopore one at a time where they will produce unique current blockade signatures for sequence determination. A large array of such nanopores will lead to high throughput DNA sequencing.

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Ultra fast optical amplifier: silicon and erbium on one chip for the first time

Within optical microchips, light finds its way through channels, waveguides, made of silicon. Light from a glass fiber, for example, is led through a structure of optical channels with splitters and couplers. Silicon is the workhorse for this, but it is still passive conduction of light, with some losses as well. To be able to amplify the signal, or even to include a light source on the chip, extra steps are necessary. Other types of semiconductors, like Gallium Arsenide, are an option. But materials doped with the rare earth material erbium have good amplification properties as well.

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Image of the chip including silicon optical waveguide (SOI: silicon on insulator) as well as erbium-doped aluminium oxyde.

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Mystery Spheres on Mars

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Using its Microscopic Imager, Opportunity photographed these small spherical objects on Sept. 6, 2012. The view covers an area about 2.4 inches across at an outcrop called "Kirkwood" on the western rim of Endeavour Crater.

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Optical Waveguide Connects Semiconductor Chips

A team of KIT researchers directed by Professor Christian Koos has succeeded in developing a novel optical connection between semiconductor chips. "Photonic wire bonding" reaches data transmission rates in the range of several terabits per second and is suited perfectly for production on the industrial scale. In the future, this technology may be used in high-performance emitter-receiver systems for optical data transmission and, thus, contribute to reducing energy consumption of the internet. The scientists published their results in the journal "Optics Express".

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The wire bond is adapted to the position and orientation of the chips.

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The search for new materials for hydrogen storage

Hydrogen is the ideal fuel for new types of fuel cell vehicles, but one problem is how to store hydrogen. In his doctoral dissertation Serhiy Luzan studies new types of materials for hydrogen storage. He also shows that new materials with interesting properties can be synthesized by the reaction of hydrogen with carbon nano-structured materials. The dissertation will be publicly defended on September 28 at Umeå University in Sweden.

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Four types of materials studied in the dissertation: fullerene C60, carbon nanotubes, metal-organic frameworks (MOFs), and fullerene C60 encapsulated inside carbon nanotubes.

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NASA Mars Rover Targets Unusual Rock on Its Journey

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The drive by NASA's Mars rover Curiosity during the mission's 43rd Martian day, or sol, (Sept. 19, 2012) ended with this rock about 8 feet (2.5 meters) in front of the rover.

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Photocatalysis as an energy source: Zn-Ga-O nanocubes improve conversion rate

As global energy demand continues to grow, the need to find a carbon-neutral and sustainable energy source for future generations has become imperative. An especially attractive solution is to store solar energy in the form of chemical fuel via artificial photosynthesis to convert carbon dioxide into hydrocarbons.

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Chinese researchers have developed a new nanomaterial to improve the chemical conversion rate in photocatalytic energy systems.

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Near-Field Enhancements along Ring-Shaped Nanostructures

Molecules close to metal nanostuctures which are illuminated by light exhibit a complex electic field. They experience electric forces along the field lines, which become very crowded in sharp regions of the nanostructures, such as corners or tips, and in the regions of high electron density. These regions of crowded field lines are called hotspots which are generally localized to small spots. If it would be possible to expand the local field enhancements to the whole sample surface, heating which limits the field enhancement could be avoided and the interaction with molecules would be increased.

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The near-field enhancement on the surface of ring-shaped gold nanostructure becomes homogeneous through circularly polarized light.

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Dawn Sees Hydrated Minerals on Giant Asteroid

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Pitted Terrain in Color
These enhanced-color views from NASA's Dawn mission show an unusual "pitted terrain" on the floors of the craters named Marcia (left) and Cornelia (right) on the giant asteroid Vesta.

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NASA's Solar Fleet Peers Into Coronal Cavities

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Scientists want to understand what causes giant explosions in the sun's atmosphere, the corona, such as this one. The eruptions are called coronal mass ejections or CMEs and they can travel toward Earth to disrupt human technologies in space. To better understand the forces at work, a team of researchers used NASA data to study a precursor of CMEs called coronal cavities.