SciTech #ScienceSunday Digest, 44/14. SciTech #ScienceSunday Digest, 44/14.DNA molecular electronics, neural turing machine, electric fields vs dark matter, terahertz circuits and fibers, uranium extraction, CRISPR genomics, plasmene nanosheets, cancer blood test, isotopic bond changes.1. Quadruplex DNA For Molecular Electronics. Specific DNA sequences have now been designed to self-assemble into long quadruplex structures that conduct electricity ift.tt/1t10RLH. For the first time reliable and well-quantified electrical current was induced and controlled through long self-assembled DNA molecules through techniques such as DNA Origami that have long been thought to be an ideal substrate for assembling molecular circuits. This current demonstration paves the way for implementing DNA-based programmable circuits for molecular electronics. The idea of mixing a solution of chemicals in a test tube to produce a computer is no longer as crazy as it sounds. 2. DeepMind’s Neural Turing Machine. The Google-acquired company DeepMind has built a new computer system dubbed a neural turing machine that can be thought of as providing a neural network with an external memory or of creating a computer with a short-term memory like the human brain ift.tt/104dsa8. This prototype system learns as it stores memories - which it is able to later access to perform tasks beyond those it had been trained to do. The system can “chunk” information in a broadly similar way to what human brains do, and draw connections between the different chunks, which it also stores in memory and can draw on to help solve more complex pattern recognition tasks. Adding a human-like hierarchy to this memory processing will be an important route of future investigation but in the interim it will be interesting to see what applications emerge from the current system. 3. Dark Matter as Galactic-Scale Electric Fields. A new result in theoretical physics suggests that the anomalous gravitational observations that birthed dark matter theories can be explained instead by galactic-scale electric fields ift.tt/1vgTRMd. The conceptual underpinning is simple: cosmically powerful activity in the centre of galaxies propels electrons from the center to the outer regions, giving the core a net positive, and the periphery a net negative charge, and setting up an electrostatic force sufficient to hold rapidly rotating galaxies together. While the amount of charge needed to provide this force is quite large at about 10^31 Coulombs, it corresponds only to 1 proton every 10^11 cubic meters, or a field strength of 1 volt per meter at the Sun’s location. Experiments and testable hypotheses will be needed, as well as solar charging mechanisms, in order to give this theory some additional weight. 4. DARPA’s Terahertz Integrated Circuits. DARPA’s Terahertz Electronics program has succeeded in creating and demonstrating a terahertz integrated circuit functioning as the fastest solid-state amplifier ever measured ift.tt/1oWj4PC. At one trillion cycles per second the circuit managed to generate an amplifier gain of 9 - 10 decibels; gains of at least 6 decibels were calculated as the amount required to build practical applications for a terahertz chip. The demonstration opens up a pathway to building practical terahertz radio radio circuits and other applications including imaging, radar, communications, and more sensitive spectrometers to name just a few. 5. 255 Terabits Over Multicore Optical Fiber. On the topic of fast terahertz wireless speeds we have a new multicore optical fiber able to provide wired data transfer speeds of 255 terabits per second ift.tt/1FR4JsF. The new optical fiber achieves this incredible speed that can provide 21 times more bandwidth than current networks with a new architecture involving seven independent cores through which light can travel as well as two additional wavelength division multiplexing techniques. This is only a factor of four away from petabit transmission rates. 6. New Approach to Extracting Uranium from Seawater. There have been a number of different technologies developed to extract uranium (and other valuable metals) from seawater in recent years and this latest effort involves the rational design of active sites in metal-organic framework (MOF) materials ift.tt/1tV7gyp. These MOFs took inspiration from enzymes and other proteins that possess high affinity for uranium and other metals, were engineered with similar binding sites, and yet produce materials that are many times lighter than proteins. Proteins typically absorb only one thousandth of their mass when capturing a uranium atom; these MOFs can absorb 20% of their mass in uranium. 7. Complex Genomic Knowledge Made Possible with CRISPR. A recent CRISPR study builds on and further extends the platform to enable the genome-wide mapping of complex genetic pathways and gene networks, and determining the genome-wide funcion of transcripts ift.tt/1ujnfXQ (paywall). The work involved generating transcriptional repressors with CRISPRi (interfering) and transcriptional activators with CRISPRa, all with minimal off-target effects and enabling the fine modulation of gene expression over a 1,000-fold range. This is a powerful, fundamental tool for generating huge amounts of information and functional knowledge about our genome and is expected to lead to insights for intervening in many if not most human diseases. 8. Fabricating Giant Plasmene Nanosheets. One particle thick, superlattice sheets of nanoparticles (dubbed plasmene due to their plasmonic properties and in reference to graphene) have been created with a new technique allowing fabrication of sheets with nanoscale thickness and lateral dimensions measuring up to three millimeters or 75,000 times long as they are thick ift.tt/1wKco6R. Once bottom-up self-assembly is complete the sheets can be patterned with conventional lithography to create nanoribbons, folded 3D plasmene origami, and other structures. Given the plasmonic light manipulation of such materials there are possible applications in light capture (solar cells, imaging), emission (lasers, displays, etc), and transmission (communications).9. A New Type of Cancer Blood Test. A new, convenient, blood-test for cancer is being developed that is based on a technology developed for testing a baby’s DNA before birth via a blood test on the mother ift.tt/1wLfo26. With the pre-natal screening the technique allows the trace amounts of the baby’s DNA circulating in the mother’s blood to be analysed and reveal complications such as Down Syndrome. Now the team has demonstrated that essentially the same technique can be used to identify genetic damage that is indicative of early-stage cancer. There are still trials and work to do to quantify its effectiveness in this application and determine the incidence of false positives / negatives but such a simple early-stage diagnostic tool would be transformative. 10. Isotopic Influences on Chemical Bonds. Recent work suggests that in certain cases the substitution of an atomic isotope complete changes the type of chemical bond that element forms ift.tt/1t10S22. Such effects are most pronounced with light atoms such as hydrogen and its isotopic derivatives deuterium, tritium, and also exotic entities such as muonium - an electron orbiting an anti-muon that behaves like a hydrogen isotope but much lighter. The research suggests that, when studying bromine at least, the conventional hydrogen isotopes from typical linear or bent bonds, whereas the muonium would form a completely and fundamentally different type of bond known as a vibrational bond. Interesting investigations into fairly fundamental states of matter. An archive of the SciTech Digests can also be found here: ift.tt/UjW6An
Posted on: Sun, 02 Nov 2014 15:11:23 +0000
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