81886867
submission
ckwu writes:
Superhydrophobic coatings that make water droplets dance and roll off of a surface show promise for applications such as self-cleaning cars, buildings, and food processing equipment. A new method creates a durable superhydrophobic coating by combining two common materials—Teflon and a shrinkable plastic—in a few simple steps. The researchers took inspiration from work done with the polystyrene material found in Shrinky Dinks--the children's crafting kit. They deposited Teflon onto a similar material called PolyShrink, heated it, and found that the Teflon formed a crinkled surface that helped water to bead and roll off easily. The best results came from putting Teflon onto polyolefin, a shrink wrap material. What's more, the surface is durable and repels water even after being scratched.
81117399
submission
ckwu writes:
Tiny rocketlike particles that move around on their own in a hydrogen peroxide solution can detect trace amounts of the lethal toxin ricin within minutes. The tube-shaped, microsized particles--made of graphene oxide lined with platinum--carry sensor molecules that glow when they bind to ricin. In a dilute hydrogen peroxide solution, the platinum catalyzes the breakdown of the peroxide into water and oxygen. The oxygen bubbles shoot out one end of the tube, propelling them in the liquid like little rockets. The swimming motors could actively seek out ricin in a sample and speed up detection, paving the way toward a quick, easy way to detect the bioterrorism agent in food and water samples without having to bring them back to a lab.
80842481
submission
ckwu writes:
Carbon nanotubes are exceptionally strong and stretchy. But so far, films made out of them have come nowhere close to having the mechanical strength of individual nanotubes. Researchers now report a simple fabrication method to make carbon nanotube films that are five times as strong as those made before—and stronger than films made from Kevlar or carbon fiber. The films had an average tensile strength of 9.6 gigapascals. By comparison, Kevlar fibers and commercially used carbon fibers are around 3.7 and 7 GPa, respectively. The films are also four times as pliable as conventional carbon fibers, able to elongate 8% on average.
80425989
submission
ckwu writes:
Last year, the news broke that in the U.S. almost 600,000 Volkswagen diesel vehicles, model years 2009 to 2015, contain software that altered engine performance and lowered emissions of toxic nitrogen oxides (NOx) during emissions tests but not during normal driving. A new study calculates the societal impact of this extra NOx: 46 excess expected deaths and $430 million in excess damages. U.S. regulators have filed a federal lawsuit against the automaker alleging violations of the Clean Air Act.
76971897
submission
ckwu writes:
Polystyrene foams—including products like Styrofoam—are rarely recycled, and the materials biodegrade so slowly that they can sit in a landfill for hundreds of years. But a pair of new studies shows that mealworms will dine on polystyrene foam when they can’t get a better meal, converting almost half of what they eat into carbon dioxide. In one study, the researchers fed mealworms polystyrene foam and found that the critters converted about 48% of the carbon they ate into carbon dioxide and excreted 49% in their feces. In the second study, the researchers showed that bacteria in the mealworms’ guts were responsible for breaking down the polystyrene--suggesting that engineering bacteria might be a strategy for boosting the reported biodegradation.
75938271
submission
ckwu writes:
A steel mesh with a novel self-cleaning coating can separate oil and water, easily lifting oil from an oil-water mixture and leaving the water behind. Unlike existing oil-water separation membranes, if the coated mesh gets contaminated with oil, it can be simply rinsed off with water and reused, without needing to be cleaned with detergents. The team was able to use the mesh to lift crude oil from a crude oil-seawater mixture, showcasing the feasibility of oil-spill cleanup. The membrane could also be used to treat oily wastewater and as a protective barrier in industrial sewer outlets to avoid oil discharge.
75330669
submission
ckwu writes:
The designs of pacemakers, watches, and other wearable gadgets have to be tailored around existing battery shapes, such as cylinders, coin cells, and rectangles. But a team of researchers hopes their fully printable, flexible lithium-ion batteries will one day free designers from these constraints. Battery shapes are now limited because of the need to contain liquid electrolytes. Two years ago, the researchers designed a printable, solid-state electrolyte composed of alumina nanoparticles and lithium combined with polymer that can be cured by ultraviolet light. In this latest work, they used a stencil printing technique to print full battery cells with the electrolyte and other printable materials for the electrodes. They printed batteries on paper and the curved surface of a glass mug. These printed Li-ion batteries can power small LEDs but still need a lot of improvements because they don't last long before needing recharging.
74487521
submission
ckwu writes:
A new transparent-paper device can generate electrical power from a user’s touch. The paper energy-harvester could be used to make disposable, self-powered touch screens that fold; interactive light-up books; touch-sensitive skin for prosthetics; and security systems for art and documents, according to the researchers. The device is made out of nanopaper, a tangled mat made of nanometers-wide cellulose fibers that is transparent and smooth like plastic. The researchers deposit carbon nanotubes on the nanopaper to make a pair of electrodes, and then sandwich a polyethylene film in between. The generator works via electrostatic induction. Pressing one side of the device causes a change in the charge balance between the nanotube electrodes, resulting in a flow of current through the device. Releasing the pressure causes electrons to flow back, so repeated pressing and releasing creates continuous current. The researchers demonstrated that the generator could produce enough power when pressed to light up a small liquid-crystal display.
73261943
submission
ckwu writes:
Researchers in South Korea have made the first quantum dots that emit ultraviolet light and used them to make a flexible, light-emitting diode. Until now, no one had succeeded in making quantum dots that emit wavelengths shorter than about 400 nm, which marks the high end of the UV spectrum. 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. If their lifetimes can be improved, these potentially low-cost UV LEDs could find uses in counterfeit currency detection, water sterilization, and industrial applications.
72750013
submission
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.
71108799
submission
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.
70249357
submission
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.
69955733
submission
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.
69242087
submission
ckwu writes:
Materials scientists have constructed round, pom-pom-like graphene microparticles by spraying graphene oxide droplets into a hot solvent—a process akin to deep-frying. The technique could provide a simple, versatile means to make electrode materials for batteries and supercapacitors, possibly leading to devices with improved energy and power densities, the researchers say. The microparticles contain graphene nanosheets radiating out from their centers, which increases the exposed surface area of the graphene and creates open nanochannels that can enhance charge transfer. Electrodes made with the graphene microspheres had higher capacitance than those made with unassembled graphene sheets, demonstrating that the 3-D structure of the particles improved performance.
65135647
submission
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.
