Slashdot Mirror

New submitter JMarshall writes: Researchers have made near-perfect reflectors out of a silicon metamaterial. These reflectors could offer a simpler, less expensive way to make high-performance mirrors for lasers or telescopes. Metamaterials typically use nanoscale patterning to create unusual properties not present in the bulk material. In this new method, researchers used off-the-shelf, nanosized polystyrene beads and allowed them to self-assemble into a monolayer with a hexagonal pattern. Using the monolayer as a photolithographic mask, the researchers etched an array of silicon cylinders, each a few hundred nanometers across, onto a wafer. The cylinders act like tiny resonators for a particular light frequency—analogous to the way a given sound frequency will make a tuning fork hum. The array reflected 99.7 % of incident light at their peak wavelength. These simple metamaterial mirrors might one day replace current high-performance reflectors, which are somewhat costly to make.

ckwu with word that South Korean researchers have created the first UV-emitting quantum dots, and employed them in the creation of a flexible LED. Their achievement is notable because no one has previously succeeded in making quantum dots capable of emitting light at wavelengths shorter than 400 nm, which defines the upper range of the UV spectrum. Writes ckwu: To get quantum dots that emit UV, the researchers figured out how make them with light-emitting cores smaller than 3 nm in diameter. They did it by coating a light-emitting cadmium zinc selenide nanoparticle with a zinc sulfide shell, which caused the core to shrink to 2.5 nm. The quantum dots give off true UV light, at 377 nm. An LED made with the quantum dots could illuminate the anticounterfeiting marks on a paper bill. The article names a few applications of the technology, besides, including water sterilization and industrial applications.

ckwu writes: To restore blood flow in a narrowed or blocked artery, doctors can implant a metal stent to hold open the vessel. But over time, stents can cause inflammation and turbulent blood flow that lead to new blockages. Now, researchers have designed a stent carrying a suite of onboard electronic blood-flow and temperature sensors, drug delivery particles, data storage, and communication capabilities to detect and overcome these problems. The entire device is designed to dissolve as the artery heals. Medical device companies and cardiologists could look at this electronic stent as a kind of menu from which they can pick whatever components are most promising for treating certain kinds of cardiovascular disease, the researchers say.

ckwu writes From bread bags to beverage bottles, many plastics now contain additives designed to make the materials biodegradable. But a new study shows that plastics made with such additives do not biodegrade in the environment significantly faster than those without the compounds. Researchers prepared films of commercial plastics with three different types of additives supplied by their manufacturers. The researchers then treated the film samples to mimic disposal of such plastics in a compost pile, a landfill, and soil. After about six months of composting, a year and a half of landfill-like conditions, and three years of soil burial, the plastics with additives did not show any more evidence of biodegradation than plastics without them.

ckwu writes Today nearly all computers, tablets, and smartphones have Wi-Fi capabilities, receiving and transmitting data over a range of radio frequencies. But a burgeoning technology known as visible light communication could someday carry those data in the same light that illuminates a room. Now a tag team of semiconducting organic polymers is bringing that dream one step closer. When excited with a blue LED, the polymer pair helps to create white light that can be rapidly switched on and off to encode information. A proof-of-principle device using the polymers sent data at 350 Mbps over a distance of 5 cm with minimal errors, a rate 35 times faster than a commercially available phosphor used for blue-light color conversion.

ckwu writes: Perfluorinated compounds help firefighting foams rapidly flow over flaming liquids such as gasoline and jet fuel, cooling and quenching fires. But despite environmental scientists' concerns about these possibly toxic compounds, researchers don't know the identity of many of the chemicals in the mixtures on the market. For the first time, a new study borrows a medical research tool to pinpoint fluorochemicals in the blood of firefighters, identifying novel compounds that have never before been publicly reported.

MTorrice writes In the U.S. alone, consumers discard over 32 million tons of plastic each year, only 9% of which is recycled. Polyethylene is one of the most popular and, unfortunately, persistent types of plastics. Bags, bottles, and packaging made from the polymer accumulate in landfills and oceans across the globe. Scientists have lamented that the material isn't biodegradable because microbes can't chew up the plastic to render it harmless. However, a new study reports the first definitive molecular evidence that two species of bacteria, found in the guts of a common pantry pest, can thrive on polyethylene and break it apart.

MTorrice writes: Many drugs that treat bacterial and fungal infections were found in microbes growing in the dirt. These organisms synthesize the compounds to fend off other bacteria and fungi around them. To find possible new drugs, chemists try to coax newly discovered microbial species to start making their arsenal of antimicrobial chemicals in the lab. But fungi can be stubborn, producing just a small set of already-known compounds.

Now, one team of chemists has hit upon a curiously effective and consistent trick to prod the organisms to start synthesizing novel molecules: Cheerios inside bags. Scientists grew a soil fungus for four weeks in a bag full of Cheerios and discovered a new compound that can block biofilm formation by an infectious yeast. The chemists claim that Cheerios are by far the best in the cereal aisle at growing chemically productive fungi.

MTorrice writes: Environmental scientists monitor particulate matter pollution because it poses risks to human health and can affect the climate. Ultrafine particles, up to 100 nm in diameter, are produced by vehicle exhaust and other combustion processes. They also form when volatile chemicals from other sources condense in the atmosphere, often through reactions triggered by sunlight.

Now atmospheric scientists propose that personal care products, such as antiperspirants, could be a potential source of ultrafine particulate matter. On the basis of data from the U.S. and Finland, they find that airborne nanoparticles in highly populated areas often contain silicon. They hypothesize that organic silicon compounds found in cosmetics waft into the air, get oxidized, and contribute to the growth of nanoparticles.

ckwu writes: Researchers have made the tiniest organic laser reported to date. The 8-micrometer-long, 440-nanometer-wide device, which looks like a suspended bridge riddled with holes, is carved into a silicon chip coated with an organic dye. Integrated into microprocessors, such tiny lasers could one day speed up computers by shuttling data using light rather than electrons. The new organic laser is optically pumped—that is, powered by pulses from another laser. But it has a very low threshold—the energy required to start lasing—of 4 microjoules per square centimeter. The low threshold brings the device closer to engineers' ultimate goal of creating an organic laser that can run on electric current, which would be key for on-chip use.

MTorrice (2611475) writes Bioengineers can harness DNA's remarkable ability to self-assemble to build two- and three-dimensional nanostructures through DNA origami. Until now, researchers using this approach have been limited to building structures that are tens of square nanometers in size. Now a team reports the largest individual DNA origami structures to date, which reach sizes of hundreds of square nanometers. What's more, they have developed a less expensive way to synthesize the DNA strands needed, overcoming a tremendous obstacle to scaling up the technology.

MTorrice (2611475) writes "Researchers have harnessed that heat from a computer CPU to run the polymerase chain reaction (PCR) to amplify DNA in a blood sample. The team developed software that cycles the temperature of the CPU to drive PCR's three distinct steps.The method allowed them to detect miniscule amounts of DNA from a pathogenic parasite that causes Chagas disease. They hope their technique will lead to low-cost diagnostic tests in developing countries." (Always good to put waste heat to a practical purpose.)

MTorrice (2611475) writes Electronics printed on paper promise to be cheap, flexible, and recyclable, and could lead to applications such as smart labels on foods and pharmaceuticals or as wearable medical sensors. Many engineers have managed to print transistors and solar cells on paper, but one key component of a smart device has been missing—memory. Now a group of researchers has developed a method that uses ink-jet technology to print resistive random access memory on an ordinary letter sized piece of paper. The memory is robust: Engineers could bend the device 1,000 times without any loss of performance. The memory is not yet very dense, but could be: "Each silver dot they printed was approximately 50 microns across and separated from its neighbor by 25 microns, so each bit of memory is 100 microns on a side. At that size, a standard 8.5- by 11-inch piece of paper can hold 1 MB of memory. Der-Hsien Lien, the paper's lead author, says existing ultrafine ink-jet technology can produce dots less than 1 micron across, which would allow the same piece of paper to hold 1 gigabyte. Reading and writing the bits takes 100 to 200 microseconds"

MTorrice writes: Plasmonic printing is a recently developed method to create color images using different shapes and sizes of gold or silver nanostructures. It relies on the oscillations of electrons in the metal surfaces and can produce images with a resolution 100 times that of a common desktop printer. Now researchers have expanded the color palette of the technique using tiny aluminum-capped nanopillars. Each pixel consists of four nanopillars; tuning the diameters and arrangement of the pillars produced a palette of more than 300 different colors. Using these pixels, the researchers created a microscale reproduction of Claude Monet's "Impression, Sunrise."

MTorrice (2611475) writes "Despite cocaine's undeniable destructiveness, there are no antidotes for overdoses or medications to fight addiction that directly neutralize cocaine's powerful effects. A natural bacterial enzyme, cocaine esterase, could help by chopping up cocaine in the bloodstream. But the enzyme is unstable in the body, losing activity too quickly to be a viable treatment. Now, using computational design, researchers tweaked the enzyme (full paper, PDF) to simultaneously increase stability and catalytic efficiency. Mice injected with the engineered enzyme survive daily lethal doses of cocaine for an average of 94 hours."

carmendrahl writes: "Lethal injections are typically regarded as far more humane methods for execution compared to predecessors such as hanging and firing squads. But the truth about the procedure's humane-ness is unclear. Major medical associations have declared involvement of their member physicians in executions to be unethical, so that means that relatively inexperienced people administer the injections. Mounting supply challenges for the lethal drug cocktails involved are forcing execution teams to change procedures on the fly. This and other problems have contributed to recent crises in Oklahoma and Missouri. As a new story and interactive graphic explains, states are turning to a number of compound cocktails to get around the supply problems."

ckwu (2886397) writes "Two independent research groups report the first transistors built entirely of two-dimensional electronic materials, making the devices some of the thinnest yet. The transistors, just a few atoms thick and hence transparent, are smaller than their silicon-based counterparts, which would allow for a super-high density of pixels in flexible, next-generation displays. The research teams, one at Argonne National Laboratory and the other at the University of California, Berkeley, used materials such as tungsten diselenide, graphene, and boron nitride to make all three components of a transistor: a semiconductor, a set of electrodes, and an insulating layer. Electrons travel in the devices 70 to 100 times faster than in amorphous silicon. Such a high electron mobility means the transistors switch faster, which dictates a display's refresh rate and is necessary for high-quality video, especially 3-D video."

MTorrice writes "Lithium-sulfur batteries promise to store four to five times as much energy as today's best lithium-ion batteries. But their short lifetimes have stood in the way of their commercialization. Now researchers demonstrate that a sulfur-based polymer could be the solution for lightweight, inexpensive batteries that store large amounts of energy. Battery electrodes made from the material have one of the highest energy-storage capacities ever reported" Litihium Ion batteries should maintain capacity for about 1000 cycles, whereas Lithium-sulfur batteries traditionally went kaput after about 100. But it looks like they are getting pretty close to something feasible, from the article: "The best performing copolymer consisted of 90% sulfur by mass. Batteries using this copolymer had an initial storage capacity of 1,225 mAh per gram of material. After 100 charge-discharge cycles, the capacity dropped to 1,005 mAh/g, and after 500 cycles it fell to about 635 mAh/g. In comparison, a lithium-ion battery typically starts out with a storage capacity of 200 mAh/g but maintains it for the life of the battery, Pyun says."

MTorrice writes "By shaving off an ultrathin layer from the top of a silicon wafer, researchers have transformed rigid electronic devices into flexible ones. The shaving process could be used to fabricate parts for wearable electronics or displays that can roll up. Compared to similar techniques to make bendable silicon electronics, the new method is more cost-effective and produces more flexible devices, its developers say."

ckwu writes "Scientists predict that the scarcity of phosphorus will increase over the next few decades as the growing demand for agricultural fertilizer depletes geologic reserves of the element. Meanwhile, phosphates released from wastewater into natural waterways can cause harmful algal blooms and low-oxygen conditions that can threaten to kill fish. Now a team of researchers has designed a system that could help solve both of these problems. It captures phosphorus from sewage waste and delivers clean water using a combined osmosis-distillation process. The system improves upon current methods by reducing the amounts of chemicals needed to precipitate a phosphorus mineral from the wastewater, thus bringing down the cost of the recovery process."

carmendrahl writes "Last fall, MIT researchers made news for developing two bioinspired cocktail toppers-- a moving cocktail boat and a floral pipette-- in collaboration with James Beard Award-winning chef José Andrés. Both the boat and floral pipette operate by taking advantage of surface tension-- either to propel the boat forward or to keep small drops of liquid inside the flower's petals. Some of those early garnishes were nominally edible. But to make them worthy of a restaurant debut requires balancing of flavors, temperature, density, and alcohol content, among other factors. Here's a look inside Andrés' company ThinkFoodGroup to see how the project is coming along. The toppers aren't available to the public just yet."

ckwu writes "The vast real estate of windows in office buildings and skyscrapers could be a fruitful field for harvesting solar energy—if lightweight solar cells could be made with a high enough conversion efficiency and appealing aesthetics. Now researchers at Oxford University report semitransparent solar cells that might do the trick. The team made solar cells using a perovskite, a class of mineral-like materials that have properties similar to inorganic semiconductors and show sunlight-to-electricity conversion efficiencies of more than 15%. The team deposited a thin film of perovskite onto glass so that the material formed tiny crystalline islands. The islands absorb photons and convert them to electrons, while light striking the empty areas passes through. The result was a semitransparent solar cell with a grayish tint."

MTorrice writes "In recent years, increasing numbers of patients worldwide have contracted severe bacterial infections that are untreatable by most available antibiotics. Some of the gravest of these infections are caused by bacteria carrying genes that confer resistance to a broad class of antibiotics called beta-lactams, many of which are treatments of last resort. Now a research team reports that some wastewater treatment plants in China discharge one of these potent resistance genes into the environment. Environmental and public health experts worry that this discharge could promote the spread of resistance."

ckwu writes "As a way to generate renewable electricity, researchers have designed methods that harvest the energy released when fresh and saline water mix, such as when a river meets the sea. One such method is called pressure-retarded osmosis, where two streams of water, one saline and one fresh, meet in a cell divided by a semipermeable membrane. Osmosis drives the freshwater across the membrane to the saltier side, increasing the pressure in the saline solution. The system keeps this salty water pressurized and then releases the pressure to spin a turbine to generate electricity. Now a team at Yale University has created a prototype device that increases the power output of pressure-retarded osmosis by an order of magnitude. At a full-scale facility, the estimated cost of the electricity generated by such a system could be 20 to 30 cents per kWh, approaching the cost of other conventional renewable energy technologies."

carmendrahl writes "Exposure to certain pesticides, including rotenone and paraquat, has been associated with a higher incidence of Parkinson's disease in population studies. But how did scientists come to think of a link between Parkinson's disease and pesticides in the first place? The answer involves the 1980s drug underworld, where criminals were synthesizing modified versions of illegal drugs such as heroin to stay one step ahead of the law. One molecule in some designer heroin cocktails, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), breaks down in the human body into 1-methyl-4-phenylpyridinium (MPP+), a nerve cell killer. Heroin addicts exposed to this molecule got Parkinson's-like symptoms. As for the connection to pesticides, MPP+ is a weed killer that was used in the 70s. It also closely resembles the structure of the pesticide paraquat. The saga, therefore, put scientists on high alert to the possibility that pesticides might play a role in developing Parkinson's."

MTorrice writes "With energy-efficient desalination techniques, water-starved communities could produce fresh water from salty sources such as seawater and industrial wastewater. But common methods like reverse osmosis require pumping the water, which uses a substantial amount of energy. So some researchers have turned to forward osmosis, because in theory it should use less energy. Now a team has demonstrated a forward osmosis system that desalinates salty water with the help of sunlight. The method uses a pair of hydrogels to absorb and squeeze out freshwater."

ckwu writes "Researchers in Japan and Taiwan have demonstrated the first working flash memory device made using proteins as scaffolding to build a 3-D nanoparticle structure. Compared to current fabrication techniques, using proteins to arrange nanoparticles could enable the design of smaller memory devices and more complex, multilayer electronics. According to the researchers, their mulitlayer flash memory had twice the capacity of a conventionally made single-layer device."

MTorrice writes "A new type of headphone heats up carbon nanotubes to crank out tunes. The tiny speaker doesn't rely on moving parts and instead produces sound through the thermoacoustic effect. When an alternating current passes through the nanotubes, the material heats and cools the air around it; as the air warms, it expands, and as it cools, it contracts. This expansion and contraction creates sound waves. The new nanotube speaker could be manufactured at low cost in the same facilities used to make computer chips, the researchers say." And it exists in the real world: "The Tsinghua researchers integrated these thermoacoustic chips into a pair of earbud headphones and connected them to a computer to play music from videos and sound files. They’ve used the headphones to play music for about a year without significant signs of wear, Yang says. According to him, this is the first thermoacoustic device to be integrated with commercial electronics and used to play music."

carmendrahl writes "Eukaryotic cells, which are defined by having a nucleus, rarely grow larger than 10 micrometers in diameter. Scientists know a few reasons why this is so. A new study suggests another reason — gravity. Studying egg cells from the frog Xenopus laevis, which reach as big as 1 mm across and are common research tools, Princeton researchers Marina Feric and Clifford Brangwynne noticed that the insides of the eggs' nuclei settled to the bottom when they disabled a mesh made from the cytoskeleton protein actin. They think the frog eggs evolved the mesh to counteract gravity, which according to their calculations becomes significant if cells get bigger than 10 micrometers in diameter."

MTorrice writes "By attaching a lightweight, inexpensive device to the back of a smart phone, scientists can convert the phone into a sensitive fluorescence microscope. The attachment [paper abstract] allows the phone's camera to take pictures of single nanoparticles and viruses, possibly providing a portable diagnostic tool for health care workers in developing countries. For example, doctors in remote regions could use the technique to measure HIV viral loads in patients' blood samples, allowing the doctors to easily monitor disease progression and determine the best course of treatment."

MTorrice writes "The same wells that energy companies drill to extract natural gas from shale formations could become repositories to store large quantities of carbon dioxide. A new computer model suggests that wells in the Marcellus shale, a 600-sq-mile formation in the northeastern U.S. that is a hotbed for gas extraction, could store half the CO2 emitted by the country's power plants from now until 2030."

carmendrahl writes "Famed astronomer Galileo Galilei is best known for taking on the Catholic Church by championing the idea that the Earth moves around the sun. But he also engaged in a debate with a philosopher about why ice floats on water. While his primary arguments were correct, he went too far, belittling legitimate, contradictory evidence given by his opponent, Ludovico delle Colombe. Galileo's erroneous arguments during the water debate are a useful reminder that the path to scientific enlightenment is not often direct and that even our intellectual heroes can sometimes be wrong."

carmendrahl writes "The abundance of shale gas in the U.S. is expected to lower the cost of petrochemicals for fuel and other applications, making it harder for plant-based, renewable feedstocks to compete in terms of price. In the search for cost-competitive crops, companies are testing plants other than traditional biofuel sources such as corn and sugarcane. In this video, you can see how a company is test-growing a relative of sugarcane, which is expected to yield 5 times the ethanol per acre compared to corn."

ckwu writes "Researchers in Hong Kong have found a beneficial new use for the electronic waste from discarded cell phones, computers, and other gadgets. Ground up into a powder, printed circuit boards from these products could sponge up another type of pollution — toxic heavy metals in water. The researchers processed the nonmetallic fraction of waste circuit boards into a powder and found that it adsorbed metals like copper, lead, and zinc more efficiently than commercially available industrial adsorbents."

MTorrice writes "A new study suggests there's more to nanoparticle toxicology than cell life and death. Although immune cells treated with iron oxide particles appeared healthy in standard toxicology tests, they struggled to perform one of their key jobs: engulfing pathogenic bacteria. The researchers wonder if exposure to significant levels of the nanoparticles could lead to dysfunction in people's immune systems."

MTorrice writes "Crab shells usually are just a nuisance that you have to crack and dig through to get the delicious meat inside. But one team of materials scientists thinks the shells could help them fabricate materials for long lasting batteries. The team used the nanostructures (abstract) found in the crustacean shells as templates to make sulfur and silicon electrode materials for lithium-ion batteries. Sulfur or silicon electrodes have a 10-times greater theoretical energy storage capacity than electrodes used in commercial batteries."

MTorrice writes "A surprising suite of microbial species colonizes plastic waste floating in the ocean, according to a new study. The bacteria appeared to burrow pits into the plastic. One possible explanation is that bacteria eat into the polymers, weakening the pieces enough to cause them to break down more quickly and eventually sink to the sea floor. While the microbes could speed the plastic's decay, they might also cause their own ecological problems, the researchers say."

First time accepted submitter ckwu writes "Scientists once thought that pathogens could not reach drinking water wells sunk into deep, protected groundwater aquifers. Nevertheless, over the past decade, researchers have identified diarrhea-causing viruses at a handful of deep bedrock well sites in the U.S. and Europe. Now, researchers report where these pathogenic viruses may have originated. The viruses appear to seep from sewer pipes and then swiftly penetrate drinking water wells. Experts recommend that public water systems might need to start testing for viruses on a routine basis."

carmendrahl writes "3-D printers don't build only solid objects anymore. They also build liquid objects, thanks to a research team at the University of Oxford. The group custom crafted a 3-D printer to squirt tiny liquid droplets from its nozzles. The 3-D patterned droplets can mimic biological tissues, such as nerve fibers, and may have potential in tissue engineering applications. An expert not involved with the study is cautious about endorsing the tissue engineering applications because they're not yet demonstrated, but praises the team for extending 3-D printing to new classes of materials."

MTorrice writes "NASA researchers have compared nuclear power to fossil fuel energy sources in terms of greenhouse gas emissions and air pollution-related deaths. Using nuclear power in place of coal and gas power has prevented some 1.8 million deaths globally over the past four decades and could save millions of more lives in coming decades, concludes their study. The pair also found that nuclear energy prevents emissions of huge quantities of greenhouse gases. These estimates help make the case that policymakers should continue to rely on and expand nuclear power in place of fossil fuels to mitigate climate change, the authors say."