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in: Energy | 2017-07-25 | by: GlobalInfoResearch

Smart toys without the batteries

The greatest challenge in entertaining young children is keeping their toys powered up. Now, one group reports in the journal ACS Sustainable Chemistry & Engineering that they are one step closer to battery-free interactive games. According to the American Academy of Pediatrics, 97 percent of children in the U.S. under the age of 4 have had some type of exposure to a mobile device. These devices are limited by the batteries' ability to hold a charge. But in order to eliminate the need for batteries, researchers must have a way to produce and store energy. Scientists are investigating options such as solar cells, like those in many calculators; supercapacitors, found in hybrid car batteries; and small specialized generators. While all these routes face challenges, current designs of triboelectric nanogenerators (TENGs) are complex, heavy, rigid and bulky. Sang-Jae Kim and colleagues wanted to make a lightweight, flexible and simple TENG that could be used in a smart interactive puzzle. The team designed a smart puzzle TENG from recycled plastics, which made it lightweight, flexible and portable. As the puzzle pieces were placed and pushed down into the proper spots, electricity was generated and an LED display indicated the letter "C" for "correct." The TENG puzzle was stable over long periods of operation time with little damage to the electrical signal. The researchers say that their smart puzzle shows that TENGs could be used in self-powered smart toys. Story Source: Materials provided by American Chemical Society. Note: Content may be edited for style and length.

in: Energy | 2017-07-24 | by: GlobalInfoResearch

Smallest particles and the vastness of the universe connected

Our observable universe is the largest object that physicists study: It spans a diameter of almost 100 billion light years. The density correlations in our universe, for example, correlations between numbers of galaxies at different parts of the universe, indicate that our vast universe has originated from a stage of cosmic inflation. On the other hand, elementary particles are the smallest object that physicists study. A particle physics Standard Model (SM) was established 50 years ago, describing all known particles and their interactions. Are density distributions of the vast universe and the nature of smallest particles related? In a recent research, scientists from HKUST and Harvard University revealed the connection between those two aspects, and argued that our universe could be used as a particle physics "collider" to study the high energy particle physics. Their findings mark the first step of cosmological collider phenomenology and pave the way for future discovery of new physics unknown yet to mankind. The research was published in the journal Physical Review Letters on June 29, 2017. "Ongoing observations of cosmological microwave background and large scale structures have achieved impressive precision, from which valuable information about primordial density perturbations can be extracted, " said Yi Wang, a co-author of the paper and an assistant professor at HKUST's department of physics. "A careful study of this SM background would be the prerequisite for using the cosmological collider to explore any new physics, and any observational signal that deviates from this background would then be a sign of physics beyond the SM." The team carried out a two-step task to work out the background of the SM model. The first step was to work out the SM spectrum during inflation, which turned out to be dramatically different from that obtained from the particle physics calculation in flat space. The second one was to figure out how the SM fields entered the cosmological density correlation functions. "Just like the line pattern of the light you see when observing a mercury lamp through a spectrometer, the mass distribution of the fundamental particles in SM also presents a special pattern, or a 'mass spectrum', which can be viewed as the fingerprint of SM," explained Zhong-Zhi Xianyu, a co-author and physicist at Center for Mathematical Sciences and Applications in Harvard University, "However, this fingerprint is subject to change if we change the ambient conditions. Just like the light spectrum changes when applying strong magnetic field to the lamp, the spectrum of the SM particles turns out to be very different at the time of inflation from it is now due to the inflationary background." The team carefully examined all effects from inflation and showed how the mass spectrum of SM would look like for different inflation models. "Through inflation, the spectrum of elementary particles is encoded in the statistics of the distribution of the contents of the universe, such as the galaxies and cosmic microwave background, that we observe today," explains Xingang Chen, a co-author and scientist in the Harvard-Smithsonian Center for Astrophysics. "This is the connection between the smallest and largest." Many problems along this direction remain to be explored. "In our minimal setup, the Standard Model particles interact with the inflaton (the driving force of inflation) rather weakly. But if some new particles can mediate stronger interactions between these two sectors, we would expect to observe a stronger signal of new physics," said Wang. "The cosmological collider is an ideal arena for new physics beyond SM." Story Source: Materials provided by Hong Kong University of Science and Technology. Note: Content may be edited for style and length.

in: Energy | 2017-07-21 | by: GlobalInfoResearch

Folding robots: No battery, no wire, no problem

The traditional Japanese art of origami transforms a simple sheet of paper into complex, three-dimensional shapes through a very specific pattern of folds, creases, and crimps. Folding robots based on that principle have emerged as an exciting new frontier of robotic design, but generally require onboard batteries or a wired connection to a power source, making them bulkier and clunkier than their paper inspiration and limiting their functionality. A team of researchers at the Wyss Institute for Biologically Inspired Engineering and the John A. Paulson School of Engineering and Applied Sciences (SEAS) at Harvard University has created battery-free folding robots that are capable of complex, repeatable movements powered and controlled through a wireless magnetic field. "Like origami, one of the main points of our design is simplicity," says co-author Je-sung Koh, Ph.D., who conducted the research as a Postdoctoral Fellow at the Wyss Institute and SEAS and is now an Assistant Professor at Ajou University in South Korea. "This system requires only basic, passive electronic components on the robot to deliver an electric current -- the structure of the robot itself takes care of the rest." The research is reported in Science Robotics. The research team's robots are flat and thin (resembling the paper on which they're based) plastic tetrahedrons, with the three outer triangles connected to the central triangle by hinges, and a small circuit on the central triangle. Attached to the hinges are coils made of a type of metal called shape-memory alloy (SMA) that can recover its original shape after deformation by being heated to a certain temperature. When the robot's hinges lie flat, the SMA coils are stretched out in their "deformed" state; when an electric current is passed through the circuit and the coils heat up, they spring back to their original, relaxed state, contracting like tiny muscles and folding the robots' outer triangles in toward the center. When the current stops, the SMA coils are stretched back out due to the stiffness of the flexure hinge, thus lowering the outer triangles back down. The power that creates the electrical current needed for the robots' movement is delivered wirelessly using electromagnetic power transmission, the same technology inside wireless charging pads that recharge the batteries in cell phones and other small electronics. An external coil with its own power source generates a magnetic field, which induces a current in the circuits in the robot, thus heating the SMA coils and inducing folding. In order to control which coils contract, the team built a resonator into each coil unit and tuned it to respond only to a very specific electromagnetic frequency. By changing the frequency of the external magnetic field, they were able to induce each SMA coil to contract independently from the others. "Not only are our robots' folding motions repeatable, we can control when and where they happen, which enables more complex movements," explains lead author Mustafa Boyvat, Ph.D., also a Postdoctoral Fellow at the Wyss Institute and SEAS. Just like the muscles in the human body, the SMA coils can only contract and relax: it's the structure of the body of the robot -- the origami "joints" -- that translates those contractions into specific movements. To demonstrate this capability, the team built a small robotic arm capable of bending to the left and right, as well as opening and closing a gripper around an object. The arm is constructed with a special origami-like pattern to permit it to bend when force is applied, and two SMA coils deliver that force when activated while a third coil pulls the gripper open. By changing the frequency of the magnetic field generated by the external coil, the team was able to control the robot's bending and gripping motions independently. There are many applications for this kind of minimalist robotic technology; for example, rather than having an uncomfortable endoscope put down their throat to assist a doctor with surgery, a patient could just swallow a micro-robot that could move around and perform simple tasks, like holding tissue or filming, powered by a coil outside their body. Using a much larger source coil -- on the order of yards in diameter -- could enable wireless, battery-free communication between multiple "smart" objects in an entire home. The team built a variety of robots -- from a quarter-sized flat tetrahedral robot to a hand-sized ship robot made of folded paper -- to show that their technology can accommodate a variety of circuit designs and successfully scale for devices large and small. "There is still room for miniaturization. We don't think we went to the limit of how small these can be, and we're excited to further develop our designs for biomedical applications," Boyvat says. "When people make micro-robots, the question is always asked, 'How can you put a battery on a robot that small?' This technology gives a great answer to that question by turning it on its head: you don't need to put a battery on it, you can power it in a different way," says corresponding author Rob Wood, Ph.D., a Core Faculty member at the Wyss Institute who co-leads its Bioinspired Robotics Platform and the Charles River Professor of Engineering and Applied Sciences at SEAS. "Medical devices today are commonly limited by the size of the batteries that power them, whereas these remotely powered origami robots can break through that size barrier and potentially offer entirely new, minimally invasive approaches for medicine and surgery in the future," says Wyss Founding Director Donald Ingber, who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children's Hospital, as well as a Professor of Bioengineering at Harvard's School of Engineering and Applied Sciences. Story Source: Materials provided by Wyss Institute for Biologically Inspired Engineering at Harvard. Original written by Lindsay Brownell. Note: Content may be edited for style and length.

in: Energy | 2017-07-17 | by: GlobalInfoResearch

Smallest-ever star discovered by astronomers

The smallest star yet measured has been discovered by a team of astronomers led by the University of Cambridge. With a size just a sliver larger than that of Saturn, the gravitational pull at its stellar surface is about 300 times stronger than what humans feel on Earth. The star is likely as small as stars can possibly become, as it has just enough mass to enable the fusion of hydrogen nuclei into helium. If it were any smaller, the pressure at the centre of the star would no longer be sufficient to enable this process to take place. Hydrogen fusion is also what powers the Sun, and scientists are attempting to replicate it as a powerful energy source here on Earth. These very small and dim stars are also the best possible candidates for detecting Earth-sized planets which can have liquid water on their surfaces, such as TRAPPIST-1, an ultracool dwarf surrounded by seven temperate Earth-sized worlds. The newly-measured star, called EBLM J0555-57Ab, is located about six hundred light years away. It is part of a binary system, and was identified as it passed in front of its much larger companion, a method which is usually used to detect planets, not stars. Details will be published in the journal Astronomy & Astrophysics. “Our discovery reveals how small stars can be,” said Alexander Boetticher, the lead author of the study, and a Master’s student at Cambridge’s Cavendish Laboratory and Institute of Astronomy. “Had this star formed with only a slightly lower mass, the fusion reaction of hydrogen in its core could not be sustained, and the star would instead have transformed into a brown dwarf.” EBLM J0555-57Ab was identified by WASP, a planet-finding experiment run by the Universities of Keele, Warwick, Leicester and St Andrews. EBLM J0555-57Ab was detected when it passed in front of, or transited, its larger parent star, forming what is called an eclipsing stellar binary system. The parent star became dimmer in a periodic fashion, the signature of an orbiting object. Thanks to this special configuration, researchers can accurately measure the mass and size of any orbiting companions, in this case a small star. The mass of EBLM J0555-57Ab was established via the Doppler, wobble method, using data from the CORALIE spectrograph. “This star is smaller, and likely colder than many of the gas giant exoplanets that have so far been identified,” said von Boetticher. “While a fascinating feature of stellar physics, it is often harder to measure the size of such dim low-mass stars than for many of the larger planets. Thankfully, we can find these small stars with planet-hunting equipment, when they orbit a larger host star in a binary system. It might sound incredible, but finding a star can at times be harder than finding a planet.” This newly-measured star has a mass comparable to the current estimate for TRAPPIST-1, but has a radius that is nearly 30% smaller. “The smallest stars provide optimal conditions for the discovery of Earth-like planets, and for the remote exploration of their atmospheres,” said co-author Amaury Triaud, senior researcher at Cambridge’s Institute of Astronomy. “However, before we can study planets, we absolutely need to understand their star; this is fundamental.” Although they are the most numerous stars in the Universe, stars with sizes and masses less than 20% that of the Sun are poorly understood, since they are difficult to detect due to their small size and low brightness. The EBLM project, which identified the star in this study, aims to plug that lapse in knowledge. “Thanks to the EBLM project, we will achieve a far greater understanding of the planets orbiting the most common stars that exist, planets like those orbiting TRAPPIST-1,” said co-author Professor Didier Queloz of Cambridge’ Cavendish Laboratory. Story Source: Materials provided by University of Cambridge. The original story is licensed under a Creative Commons License. Note: Content may be edited for style and length.

in: Energy | 2017-07-13 | by: GlobalInfoResearch

'Near-zero-power' temperature sensor could make wearables, smart devices less power-hungry

Electrical engineers at the University of California San Diego have developed a temperature sensor that runs on only 113 picowatts of power -- 628 times lower power than the state of the art and about 10 billion times smaller than a watt. This near-zero-power temperature sensor could extend the battery life of wearable or implantable devices that monitor body temperature, smart home monitoring systems, Internet of Things devices and environmental monitoring systems. The technology could also enable a new class of devices that can be powered by harvesting energy from low-power sources, such as the body or the surrounding environment, researchers said. The work was published in Scientific Reports on June 30. "Our vision is to make wearable devices that are so unobtrusive, so invisible that users are virtually unaware that they're wearing their wearables, making them 'unawearables.' Our new near-zero-power technology could one day eliminate the need to ever change or recharge a battery," said Patrick Mercier, an electrical engineering professor at UC San Diego Jacobs School of Engineering and the study's senior author. "We're building systems that have such low power requirements that they could potentially run for years on just a tiny battery," said Hui Wang, an electrical engineering Ph.D. student in Mercier's lab and the first author of the study. Building ultra-low power, miniaturized electronic devices is the theme of Mercier's Energy-Efficient Microsystems lab at UC San Diego. Mercier also serves as co-director for the Center for Wearable Sensors at UC San Diego. A big part of his group's work focuses on boosting energy efficiencies of individual parts of an integrated circuit in order to reduce the power requirement of the system as a whole. One example is the temperature sensor found in healthcare devices or smart thermostats. While the power requirement of state-of-the-art temperature sensors has been reduced to as low as tens of nanowatts, the one developed by Mercier's group runs on just 113 picowatts -- 628 times lower power. Minimizing power Their new approach involves minimizing power in two domains: the current source and the conversion of temperature to a digital readout. Researchers built an ultra-low power current source using what are called "gate leakage" transistors -- transistors in which tiny levels of current leak through the electronic barrier, or the gate. Transistors typically have a gate that can turn on and off the flow of electrons. But as the size of modern transistors continues to shrink, the gate material becomes so thin that it can no longer block electrons from leaking through -- a phenomenon known as the quantum tunneling effect. Gate leakage is considered problematic in systems such as microprocessors or precision analog circuits. Here, researchers are taking advantage of it -- they're using these minuscule levels of electron flow to power the circuit. "Many researchers are trying to get rid of leakage current, but we are exploiting it to build an ultra-low power current source," Hui said. Using these current sources, researchers developed a less power-hungry way to digitize temperature. This process normally requires passing current through a resistor -- its resistance changes with temperature -- then measuring the resulting voltage, and then converting that voltage to its corresponding temperature using a high power analog to digital converter. Instead of this conventional process, researchers developed an innovative system to digitize temperature directly and save power. Their system consists of two ultra-low power current sources: one that charges a capacitor in a fixed amount of time regardless of temperature, and one that charges at a rate that varies with temperature -- slower at lower temperatures, faster at higher temperatures. As the temperature changes, the system adapts so that the temperature-dependent current source charges in the same amount of time as the fixed current source. A built-in digital feedback loop equalizes the charging times by reconnecting the temperature-dependent current source to a capacitor of a different size -- the size of this capacitor is directly proportional to the actual temperature. For example, when the temperature falls, the temperature-dependent current source will charge slower, and the feedback loop compensates by switching to a smaller capacitor, which dictates a particular digital readout. The temperature sensor is integrated into a small chip measuring 0.15 × 0.15 square millimeters in area. It operates at temperatures ranging from minus 20 C to 40 C. Its performance is fairly comparable to that of the state of the art even at near-zero-power, researchers said. One tradeoff is that the sensor has a response time of approximately one temperature update per second, which is slightly slower than existing temperature sensors. However, this response time is sufficient for devices that operate in the human body, homes and other environments where temperature do not fluctuate rapidly, researchers said. Moving forward, the team is working to improve the accuracy of the temperature sensor. The team is also optimizing the design so that it can be successfully integrated into commercial devices. Story Source: Materials provided by University of California - San Diego. Note: Content may be edited for style and length.

in: Energy | 2017-07-13 | by: GlobalInfoResearch

In the fast lane: Conductive electrodes are key to fast-charging batteries

Can you imagine fully charging your cell phone in just a few seconds? Researchers in Drexel University's College of Engineering can, and they took a big step toward making it a reality with their recent work unveiling of a new battery electrode design in the journal Nature Energy. The team, led by Yury Gogotsi, PhD, Distinguished University and Bach professor in Drexel's College of Engineering, in the Department of Materials Science and Engineering, created the new electrode designs from a highly conductive, two-dimensional material called MXene. Their design could make energy storage devices like batteries, viewed as the plodding tanker truck of energy storage technology, just as fast as the speedy supercapacitors that are used to provide energy in a pinch -- often as a battery back-up or to provide quick bursts of energy for things like camera flashes. "This paper refutes the widely accepted dogma that chemical charge storage, used in batteries and pseudocapacitors, is always much slower than physical storage used in electrical double-layer capacitors, also known as supercapacitors," Gogotsi said. "We demonstrate charging of thin MXene electrodes in tens of milliseconds. This is enabled by very high electronic conductivity of MXene. This paves the way to development of ultrafast energy storage devices than can be charged and discharged within seconds, but store much more energy than conventional supercapacitors." The key to faster charging energy storage devices is in the electrode design. Electrodes are essential components of batteries, through which energy is stored during charging and from which it is disbursed to power our devices. So the ideal design for these components would be one that allows them to be quickly charged and store more energy. To store more energy, the materials should have places to put it. Electrode materials in batteries offer ports for charge to be stored. In electrochemistry, these ports, called "redox active sites" are the places that hold an electrical charge when each ion is delivered. So if the electrode material has more ports, it can store more energy -- which equates to a battery with more "juice." Collaborators Patrice Simon, PhD, and Zifeng Lin, from Université Paul Sabatier in France, produced a hydrogel electrode design with more redox active sites, which allows it to store as much charge for its volume as a battery. This measure of capacity, termed "volumetric performance," is an important metric for judging the utility of any energy storage device. To make those plentiful hydrogel electrode ports even more attractive to ion traffic, the Drexel-led team, including researchers Maria Lukatskaya, PhD, Sankalp Kota, a graduate student in Drexel's MAX/MXene Research Group led by Michel Barsoum, PhD, distinguished professor in the College of Engineering; and Mengquiang Zhao, PhD, designed electrode architectures with open macroporosity -- many small openings -- to make each redox active sites in the MXene material readily accessible to ions. "In traditional batteries and supercapacitors, ions have a tortuous path toward charge storage ports, which not only slows down everything, but it also creates a situation where very few ions actually reach their destination at fast charging rates," said Lukatskaya, the first author on the paper, who conducted the research as part of the A.J. Drexel Nanomaterials Institute. "The ideal electrode architecture would be something like ions moving to the ports via multi-lane, high-speed 'highways,' instead of taking single-lane roads. Our macroporous electrode design achieves this goal, which allows for rapid charging -- on the order of a few seconds or less." The overarching benefit of using MXene as the material for the electrode design is its conductivity. Materials that allow for rapid flow of an electrical current, like aluminum and copper, are often used in electric cables. MXenes are conductive, just like metals, so not only do ions have a wide-open path to a number of storage ports, but they can also move very quickly to meet electrons there. Mikhael Levi, PhD, and Netanel Shpigel, research collaborators from Bar-Ilan University in Israel, helped the Drexel group maximize the number of the ports accessible to ions in MXene electrodes. Use in battery electrodes is just the latest in a series of developments with the MXene material that was discovered by researchers in Drexel's Department of Materials Science and Engineering in 2011. Since then, researchers have been testing them in a variety of applications from energy storage to electromagnetic radiation shielding, and water filtering. This latest development is significant in particular because it addresses one of the primary problems hindering the expansion of the electric vehicle market and that has been lurking on the horizon for mobile devices. "If we start using low-dimensional and electronically conducting materials as battery electrodes, we can make batteries working much, much faster than today," Gogotsi said. "Eventually, appreciation of this fact will lead us to car, laptop and cell-phone batteries capable of charging at much higher rates -- seconds or minutes rather than hours." Story Source: Materials provided by Drexel University. Note: Content may be edited for style and length.

in: Energy | 2017-07-06 | by: GlobalInfoResearch

Under pressure: Extreme atmosphere stripping may limit exoplanets' habitability

New models of massive stellar eruptions hint at an extra layer of complexity when considering whether an exoplanet may be habitable or not. Models developed for our own Sun have now been applied to cool stars favoured by exoplanet hunters, in research presented by Dr Christina Kay, of the NASA Goddard Flight Center, on Monday 3rd July at the National Astronomy Meeting at the University of Hull. Coronal mass ejections (CMEs) are huge explosions of plasma and magnetic field that routinely erupt from the Sun and other stars. They are a fundamental factor in so called "space weather," and are already known to potentially disrupt satellites and other electronic equipment on Earth. However, scientists have shown that the effects of space weather may also have a significant impact on the potential habitability of planets around cool, low mass stars -- a popular target in the search for Earth-like exoplanets. Traditionally an exoplanet is considered "habitable" if its orbit corresponds to a temperature where liquid water can exist. Low mass stars are cooler, and therefore should have habitable zones much closer in to the star than in our own solar system, but their CMEs should be much stronger due to their enhanced magnetic fields. When a CME impacts a planet, it compresses the planet's magnetosphere, a protective magnetic bubble shielding the planet. Extreme CMEs can exert enough pressure to shrink a magnetosphere so much that it exposes a planet's atmosphere, which can then be swept away from the planet. This could in turn leave the planetary surface and any potential developing lifeforms exposed to harmful X-rays from the nearby host star. The team built on recent work done at Boston University, taking information about CMEs in our own solar system and applying it to a cool star system. "We figured that the CMEs would be more powerful and more frequent than solar CMEs, but what was unexpected was where the CMEs ended up" said Christina Kay, who led the research during her PhD work. The team modelled the trajectory of theoretical CMEs from the cool star V374 Pegasi and found that the strong magnetic fields of the star push most CMEs down to the Astrophysical Current Sheet (ACS), the surface corresponding to the minimum magnetic field strength at each distance, where they remain trapped. "While these cool stars may be the most abundant, and seem to offer the best prospects for finding life elsewhere, we find that they can be a lot more dangerous to live around due to their CMEs" said Marc Kornbleuth, a graduate student involved in the project. The results suggest that an exoplanet would need a magnetic field ten to several thousand times that of Earth's to shield their atmosphere from the cool star's CMEs. As many as five impacts a day could occur for planets near the ACS, but the rate decreases to one every other day for planets with an inclined orbit. Merav Opher, who advised the work, commented, "This work is pioneering in the sense that we are just now starting to explore space weather effects on exoplanets, which will have to be taken into account when discussing the habitability of planets near very active stars." Story Source: Materials provided by Royal Astronomical Society. Note: Content may be edited for style and length.

in: Energy | 2017-07-04 | by: GlobalInfoResearch

The sharpest laser in the world

No one had ever come so close to the ideal laser before: theoretically, laser light has only one single color (also frequency or wavelength). In reality, however, there is always a certain linewidth. With a linewidth of only 10 mHz, the laser that the researchers from the Physikalisch-Technische Bundesanstalt (PTB) have now developed together with US researchers from JILA, a joint institute of the National Institute of Standards and Technology and the University of Colorado Boulder, has established a new world record. This precision is useful for various applications such as optical atomic clocks, precision spectroscopy, radioastronomy and for testing the theory of relativity. The results have been published in the current issue of Physical Review Letters. Lasers were once deemed a solution without problems -- but that is now history. More than 50 years have passed since the first technical realization of the laser, and we cannot imagine how we could live without them today. Laser light is used in numerous applications in industry, medicine and information technologies. Lasers have brought about a real revolution in many fields of research and in metrology -- or have even made some new fields possible in the first place. One of a laser's outstanding properties is the excellent coherence of the emitted light. For researchers, this is a measure for the light wave's regular frequency and linewidth. Ideally, laser light has only one fixed wavelength (or frequency). In practice, the spectrum of most types of lasers can, however, reach from a few kHz to a few MHz in width, which is not good enough for numerous experiments requiring high precision. Research has therefore focused on developing ever better lasers with greater frequency stability and a narrower linewidth. Within the scope of a nearly 10-year-long joint project with the US colleagues from JILA in Boulder, Colorado, a laser has now been developed at PTB whose linewidth is only 10 mHz (0.01 Hz), hereby establishing a new world record. "The smaller the linewidth of the laser, the more accurate the measurement of the atom's frequency in an optical clock. This new laser will enable us to decisively improve the quality of our clocks," PTB physicist Thomas Legero explains. In addition to the new laser's extremely small linewidth, Legero and his colleagues found out by means of measurements that the emitted laser light's frequency was more precise than what had ever been achieved before. Although the light wave oscillates approx. 200 trillion times per second, it only gets out of sync after 11 seconds. By then, the perfect wave train emitted has already attained a length of approx. 3.3 million kilometers. This length corresponds to nearly ten times the distance between Earth and the moon. Since there was no other comparably precise laser in the world, the scientists working on this collaboration had to set up two such laser systems straight off. Only by comparing these two lasers was it possible to prove the outstanding properties of the emitted light. The core piece of each of the lasers is a 21-cm long Fabry-Pérot silicon resonator. The resonator consists of two highly reflecting mirrors which are located opposite each other and are kept at a fixed distance by means of a double cone. Similar to an organ pipe, the resonator length determines the frequency of the wave which begins to oscillate, i.e., the light wave inside the resonator. Special stabilization electronics ensure that the light frequency of the laser constantly follows the natural frequency of the resonator. The laser's frequency stability -- and thus its linewidth -- then depends only on the length stability of the Fabry-Pérot resonator. The scientists at PTB had to isolate the resonator nearly perfectly from all environmental influences which might change its length. Among these influences are temperature and pressure variations, but also external mechanical perturbations due to seismic waves or sound. They have attained such perfection in doing so that the only influence left was the thermal motion of the atoms in the resonator. This "thermal noise" corresponds to the Brownian motion in all materials at a finite temperature, and it represents a fundamental limit to the length stability of a solid. Its extent depends on the materials used to build the resonator as well as on the resonator's temperature. For this reason, the scientists of this collaboration manufactured the resonator from single-crystal silicon which was cooled down to a temperature of -150 °C. The thermal noise of the silicon body is so low that the length fluctuations observed only originate from the thermal noise of the dielectric SiO2/Ta2O5 mirror layers. Although the mirror layers are only a few micrometers thick, they dominate the resonator's length stability. In total, the resonator length, however, only fluctuates in the range of 10 attometers. This length corresponds to no more than a ten-millionth of the diameter of a hydrogen atom. The resulting frequency variations of the laser therefore amount to less than 4 × 10-17 of the laser frequency. The new lasers are now being used both at PTB and at JILA in Boulder to further improve the quality of optical atomic clocks and to carry out new precision measurements on ultracold atoms. At PTB, the ultrastable light from these lasers is already being distributed via optical waveguides and is then used by the optical clocks in Braunschweig. "In the future, it is planned to disseminate this light also within a European network. This plan would allow even more precise comparisons between the optical clocks in Braunschweig and the clocks of our European colleagues in Paris and London," Legero says. In Boulder, a similar plan is in place to distribute the laser across a fiber network that connects between JILA and various NIST labs. The scientists from this collaboration see further optimization possibilities. With novel crystalline mirror layers and lower temperatures, the disturbing thermal noise can be further reduced. The linewidth could then even become smaller than 1 mHz. Story Source: Materials provided by Physikalisch-Technische Bundesanstalt (PTB). Note: Content may be edited for style and length.

in: Energy | 2017-06-30 | by: GlobalInfoResearch

Air pollution casts shadow over solar energy production

Global solar energy production is taking a major hit due to air pollution and dust. According to a new study, airborne particles and their accumulation on solar cells are cutting energy output by more than 25 percent in certain parts of the world. The regions hardest hit are also those investing the most in solar energy installations: China, India and the Arabian Peninsula. The study appears online June 23 in Environmental Science & Technology Letters. "My colleagues in India were showing off some of their rooftop solar installations, and I was blown away by how dirty the panels were," said Michael Bergin, professor of civil and environmental engineering at Duke University and lead author of the study. "I thought the dirt had to affect their efficiencies, but there weren't any studies out there estimating the losses. So we put together a comprehensive model to do just that." With colleagues at the Indian Institute of Technology-Gandhinagar and the University of Wisconsin at Madison, Bergin measured the decrease in solar energy gathered by the IITGN's solar panels as they became dirtier over time. The data showed a 50-percent jump in efficiency each time the panels were cleaned after being left alone for several weeks. The researchers also sampled the grime to analyze its composition, revealing that 92 percent was dust while the remaining fraction was composed of carbon and ion pollutants from human activity. While this may sound like a small amount, light is blocked more efficiently by smaller humanmade particles than by natural dust. As a result, the human contributions to energy loss are much greater than those from dust, making the two sources roughly equal antagonists in this case. "The humanmade particles are also small and sticky, making them much more difficult to clean off," said Bergin. "You might think you could just clean the solar panels more often, but the more you clean them, the higher your risk of damaging them." Having previously analyzed pollutants discoloring India's Taj Mahal, Bergin already had a good idea of how these different particles react to sunlight. Using his earlier work as a base, he created an equation that accurately estimates the amount of sunlight blocked by different compositions of solar panel dust and pollution buildup. But grimy buildup on solar panels isn't the only thing blocking sunlight -- the ambient particles in the air also have a screening effect. For that half of the sun-blocking equation, Bergin turned to Drew Shindell, professor of climate sciences at Duke and an expert in using the NASA GISS Global Climate Model. Because the climate model already accounts for the amount of the sun's energy blocked by different types of airborne particles, it was not a stretch to estimate the particles' effects on solar energy. The NASA model also estimates the amount of particulate matter deposited on surfaces worldwide, providing a basis for Bergin's equation to calculate how much sunlight would be blocked by accumulated dust and pollution. The resulting calculations estimate the total loss of solar energy production in every part of the world. While the United States has relatively little migratory dust, more arid regions such as the Arabian Peninsula, Northern India and Eastern China are looking at heavy losses -- 17 to 25 percent or more, assuming monthly cleanings. If cleanings take place every two months, those numbers jump to 25 or 35 percent. There are, of course, multiple variables that affect solar power production both on a local and regional level. For example, a large construction zone can cause a swift buildup of dust on a nearby solar array. The Arabian Peninsula loses much more solar power to dust than it does humanmade pollutants, Bergin said. But the reverse is true for regions of China, and regions of India are not far behind. "China is already looking at tens of billions of dollars being lost each year, with more than 80 percent of that coming from losses due to pollution," said Bergin. "With the explosion of renewables taking place in China and their recent commitment to expanding their solar power capacity, that number is only going to go up." "We always knew these pollutants were bad for human health and climate change, but now we've shown how bad they are for solar energy as well," continued Bergin. "It's yet another reason for policymakers worldwide to adopt emissions controls." This work was supported by the US Agency for International Development and the Office of the Vice Provost for Research at Duke University. Story Source: Materials provided by Duke University. Original written by Ken Kingery. Note: Content may be edited for style and length.

in: Energy | 2017-06-23 | by: GlobalInfoResearch

Flexible wearable electronics use body heat for energy

In a proof-of-concept study, North Carolina State University engineers have designed a flexible thermoelectric energy harvester that has the potential to rival the effectiveness of existing power wearable electronic devices using body heat as the only source of energy. Wearable devices used to monitor a variety of health and environmental measures are becoming increasingly popular. The performance and efficiency of flexible devices, however, pale in comparison to rigid devices, which have been superior in their ability to convert body heat into usable energy. "We wanted to design a flexible thermoelectric harvester that does not compromise on the material quality of rigid devices yet provides similar or better efficiency," said Mehmet Ozturk, a professor of electrical and computer engineering at NC State and corresponding author of a paper describing the work. "Using rigid devices is not the best option when you consider a number of different factors." Ozturk mentioned superior contact resistance -- or skin contact -- with flexible devices, as well as the ergonomic and comfort considerations to the device wearer. Ozturk said that he and colleagues Michael Dickey and Daryoosh Vashaee wanted to utilize the best thermoelectric materials used in rigid devices in a flexible package, so that manufacturers wouldn't need to develop new materials when creating flexible devices. Ozturk said one of the key challenges of a flexible harvester is to connect thermoelectric elements in series using reliable, low-resistivity interconnects. "We use a liquid metal of gallium and indium -- a common, non-toxic alloy called EGaIn -- to connect the thermoelectric 'legs,'" Ozturk said. "The electric resistance of these connections is very low, which is critical since the generated power is inversely proportional to the resistance: Low resistance means more power. "Using liquid metal also adds a self-healing function: If a connection is broken, the liquid metal will reconnect to make the device work efficiently again. Rigid devices are not able to heal themselves," Ozturk added. Ozturk said future work will focus on improving the efficiencies of these flexible devices, by using materials and techniques to further eliminate parasitic resistances. Dickey, Vashaee, Francisco Suarez, Dishit P. Parekh and Collin Ladd co-authored the paper, which appears in Applied Energy. The group also has a pending patent application on the technology. Story Source: Materials provided by North Carolina State University. Note: Content may be edited for style and length.

On: 2018-06-22

Global Citric Acid Market Expected To Reach USD 1805.1 M USD By 2024

Global Citric Acid Market expected to reach USD 1805.1 M USD by 2024 driven by its increasing use in Food & Beverages, Pharmaceuticals & Personal Care and Detergents & Cleansers. The growth of these end-use industries, particularly in emerging economies of Asia Pacific region, is anticipated to boost the growth of the chemical over the projected period. There are many manufacturers in the world, mainly in china, North America and Europe. The major manufacturers are Weifang Ensign Industry Co., Ltd., TTCA Co., Ltd, RZBC Group Co. Ltd., Cofco Biochemical (Anhui) Co., Ltd., Jungbunzlauer Suisse AG, Tate & Lyle, S.A. Citrique Belge N.V., Archer Daniels Midland Company, Cargill Incorporated, Shandong Juxian Hongde Citric Acid Company Ltd and Huangshi Xinghua Biochemical Co.Ltd. The product revenue of Citric Acid is 1685.8 M USD in 2016. Browse Related Reports: Global Citric Acid Market by Manufacturers, Countries, Type and Application, Forecast to 2022 http://www.globalinforesearch.com/goods.php?id=30743 Global (North America, Europe and Asia-Pacific, South America, Middle East and Africa) Citric Acid Market 2017 Forecast to 2022 http://www.globalinforesearch.com/goods.php?id=30704 The bio-based and chelating characteristics of citric acid make it a viable solution to several toxic substances used for manufacturing detergents & cleaners, especially for household purposes. Rising awareness regarding cleanliness and hygiene is expected to augment the demand for detergents & cleaners, resulting in a volume CAGR of 5.23% over the projected period. Asia Pacific dominated the global industry, the Product Capacity accounted for above 67% of the global citric acid market in 2016.but the major consumption regions are Europe and North America, the consumption market share are 31.19% and 25.34% in 2016. Rapid industrialization resulting in the presence of large-scale manufacturing bases for food & beverages, pharmaceuticals, and cosmetics is expected to augment the demand for the chemical as an intermediate in several processes. Increasing healthcare expenditure coupled with rising number of ailments across the world is expected to augment the demand for pharmaceuticals. The demand for citric acid is projected to progress in tandem with the development of the pharmaceutical sector. GLOBAL INFO RESEARCH ALL RIGHTS RESERVED Contact us: Tel:00852-58197708 (HK) Email:sales@globalinforesearch.com

by: GlobalInfoResearch