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.
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.
JMarshall writes: A new, elastic silver ink allows stretchy circuits to be drawn using a regular pen. Unlike previous inks, which have been made with silver nanoparticles and are prone to clog pens over time, this ink begins as a silver salt mixed with adhesive rubber. After writing, the ink is brushed with a formaldehyde and sodium hydroxide solution that reduces the silver ions to conductive silver nanoparticles. Researchers strung 14 LED lights together using the ink. The lights stayed lit even through stretching and bending the rubber sheet the circuit was drawn on.
ckwu writes: As 3-D printers become cheaper and more popular, researchers are starting to investigate the potential health and environmental impacts of the technology. A new study shows that parts made by a common 3-D printing method, stereolithography, are toxic to zebrafish, a model organism often used to predict toxicological effects on humans. The researchers hypothesize that acrylate and methacrylate monomers in the resin that don't get fully polymerized could be leaching from the parts. On the other hand, 3-D-printed parts made with another technique, fused deposition modeling, didn't appear to be toxic to zebrafish. The findings are too preliminary to draw conclusions about human toxicity, but they suggest that 3-D printing waste should be carefully managed to prevent harm to ecosystems.
JMarshall writes: Wildflowers growing near fields sown with pesticide-treated seeds can be reservoirs of bee-harming neonicotinoid compounds, according to new research. The study suggests bees get most of their exposure to these pesticides from wildflowers, rather than from the crops the pesticides are designed to protect. At the peak of flowering season, 97% of the pollen brought back to beehives tested in the UK came from wildflowers, not the canola crops they were growing alongside.
JMarshall writes: Impossible Foods, a Silicon Valley food start-up started by a Stanford professor who quit his job, just raised $108 million to pursue a plant-based burger that truly tastes like meat. This article explains how Impossible Foods and other startups and researchers are tackling the tricky chemical and engineering challenge of making fake meat that tastes real.
JMarshall writes: Adding cellulose nanofibers to paper pulp creates paper that can be recycled more than twice as many times as regular paper. In the past few years, researchers have been interested in making paper with nanometers-wide cellulose fibers in addition to regular fibers. The high surface area of such nanofibers lets them form more bonds with adjacent fibers, resulting in tougher paper.
In a new study, researchers recycled standard paper several times by using either conventional mechanical recycling techniques or by adding 3% by weight of cellulose nanofibers to the paper pulp at each cycle. Conventional recycling made the sheets unusable for writing after three cycles, whereas the nanofiber-treated paper could be recycled seven times.
The researchers also conducted a preliminary life-cycle assessment of the environmental impact of the two techniques. The two recycling techniques had a similar environmental impact, but the researchers expect that future efficiency gains in the nanofiber production process could give nanofiber paper an environmental edge.
JMarshall writes: Self-propelled nanoparticles autonomously detect surface cracks in circuit wiring and then nestle into the cracks to patch them. To fix a broken circuit, a drop of the nanoparticle-containing solution could be placed on the surface of the circuit without needing to pinpoint the location of the damage.
One hemisphere of each gold nanoparticle is coated with platinum, which catalyzes a reaction with hydrogen peroxide into water that creates a concentration gradient and pushes the particles around. The other hemisphere is coated with a hydrophobic molecule that sticks when it encounters a hydrophobic surface, like the exposed silicon beneath cracks in wiring on a circuit board. When it sticks in the crack site, the gold nanoparticle bridges the gap and current can flow again. Researchers demonstrate that they could fix a circuit and relight an LED within five minutes of applying the particles.
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.
MTorrice writes: Our chromosomes hold a partial record of prehistoric viral infections: About 8% of our genomes come from DNA that viruses incorporated into the cells of our ancestors. Over many millennia, these viral genes have accumulated mutations rendering them mostly dormant.
But one of these viruses can reawaken in some patients with amyotrophic lateral sclerosis (ALS), a progressive muscle wasting disease commonly known as Lou Gehrig’s disease. A new study demonstrates that this so-called endogenous retrovirus can damage neurons, possibly contributing to the neurodegeneration seen in the disease.
The findings raise the possibility that antiretroviral drugs, similar to those used to treat HIV, could slow the progression of ALS in some patients.
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.
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.
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.
MTorrice writes: When bugs explode against the wings of oncoming airplanes, they create a sticky problem for aerospace engineers. Their blood, or hemolymph, clings to an airplane’s wings, disrupting the smooth airflow over them and sapping the aircraft’s fuel efficiency. NASA scientists are now developing coatings that help aircraft shed or repel bug guts during flight. After screening nearly 200 different coating formulations, the NASA researchers recently flight-tested a handful of promising candidates, showing that they could reduce the amount of insect insides stuck to the wings by up to 40%. With further optimization, such coatings could allow planes to use 5% less fuel.