PhotosynthesisResearchers have traced the paths of three water channels in an ancient photosynthetic organism—a strain of cyanobacteria—to provide the first comprehensive, experimental study of how that organism uses and regulates water to create energy.

The finding advances photosynthesis research but also presents an advance in green fuels research.

Photosynthesis is the chemical conversion of sunlight into chemical energy via an electron transport chain essential to nearly all life on our planet. All plants operate by photosynthesis, as do algae and certain varieties of bacteria.

‘Damage trails’

To convert sunlight into a usable form of energy, photosynthetic organisms require water at the “active site” of the Photosystem II protein complex. But the channels through which water arrives at the active site are difficult to measure experimentally. Reactive oxygen species are produced at the active site and travel away from it, in the opposite direction as water, leaving a “damage trail” in their wake.

“We identified the damaged sites in Photosystem II using high-resolution mass spectrometry and found that they reveal several pathways centered on the active site and leading away from it all the way to the surface of the complex,” says lead study author Daniel A. Weisz, a postdoctoral researcher in biology at Washington University in St. Louis.

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GraphenePillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, report engineers.

Materials scientist Rouzbeh Shahsavari of Rice University and alumnus Navid Sakhavand first built atom-level computer models of pillared graphene—sheets of graphene connected by covalently bonded carbon nanotubes—to discover their strength and electrical properties as well as their thermal conductivity.

In a new study, they found that manipulating the joints between the nanotubes and graphene has a significant impact on the material’s ability to direct heat. That could be important as electronic devices shrink and require more sophisticated heat sinks.

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A reversible fabric keeps skin a comfortable temperature whatever the weather—and could save energy by keeping us away from the thermostat.

As reported in Science Advances, the double-sided fabric is based on the same material as everyday kitchen wrap and can offer warmth or cooling depending on which side faces out.

“Why do you need to cool and heat the whole building? Why don’t you cool and heat individual people?” says Yi Cui, professor of materials science and engineering at Stanford University, who thought if people could be more comfortable in a range of temperatures, they could save energy on air conditioning and central heating.

Thirteen percent of all of the energy consumed in the United States is due to indoor temperature control. But for every 1 degree Celsius (1.8 degrees Fahrenheit) that a thermostat is turned down, a building can save a whopping 10 percent of its heating energy—and the reverse is true for cooling. So adjusting temperature controls by just a few degrees could have major effects on energy consumption.

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Researchers have developed a type of “smart paper” that can conduct electricity and detect water.

The paper, laced with conductive nanomaterials, can be employed as a switch, turning on or off an LED light, or as an alarm system indicating the absence or presence of water.

In cities and large-scale manufacturing plants, a water leak in a complicated network of pipes can take tremendous time and effort to detect, as technicians must disassemble many pieces to locate the problem.

The American Water Works Association indicates that nearly a quarter-million water line breaks occur each year in the United States, costing public water utilities about $2.8 billion annually.

The smart paper could simplify the process for discovering detrimental leaks.

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PolymerA method to overcome the inherent trade-off between strength and flexibility in certain types of polymers gets inspiration from the tough, flexible polymeric byssal threads that marine mussels use to secure themselves to surfaces in the rugged intertidal zone.

A wide range of polymer-based materials, from tire rubber and wetsuit neoprene to Lycra clothing and silicone, are elastomers valued for their ability to flex and stretch without breaking and return to their original form.

Making such materials stronger, however, usually means making them more brittle. That’s because, structurally, elastomers are rather shapeless networks of polymer strands—often compared to a bundle of disorganized spaghetti noodles—held together by a few chemical cross-links.

Strengthening a polymer requires increasing the density of cross-links between the strands by creating more links. This causes the elastomer’s strands to resist stretching away from each other, giving the material a more organized structure but also making it stiffer and more prone to failure.

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GrapheneScientists have learned how to tame the unruly electrons in graphene.

Graphene is a nano-thin layer of the carbon-based graphite in pencils. It is far stronger than steel and a great conductor. But when electrons move through it, they do so in straight lines and their high velocity does not change. “If they hit a barrier, they can’t turn back, so they have to go through it,” says Eva Y. Andrei, professor in the Rutgers University-New Brunswick department of physics and astronomy and the study’s senior author.

“People have been looking at how to control or tame these electrons.”

Graphene is a better conductor than copper and is very promising for electronic devices.

The new research “shows we can electrically control the electrons in graphene,” says Andrei. “In the past, we couldn’t do it. This is the reason people thought that one could not make devices like transistors that require switching with graphene, because their electrons run wild.”

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Corroded pipelinesA new device has given scientists a nanoscale glimpse of crevice and pitting corrosion as it happens.

Corrosion affects almost everything made of metal—cars, boats, underground pipes, and even the fillings in your teeth.

It carries a steep price tag—trillions of dollars annually—not mention, the potential safety, environmental, and health hazards it poses.

“Corrosion has been a major problem for a very long time,” says Jacob Israelachvili, a chemical engineering professor at the University of California, Santa Barbara.

Confined spaces

Particularly in confined spaces—thin gaps between machine parts, the contact area between hardware and metal plate, behind seals and under gaskets, seams where two surfaces meet—close observation of such electrochemical dissolution had been an enormous challenge. But, not any more.

Using a device called the Surface Forces Apparatus (SFA), Israelachvili and colleagues were able to get a real-time look at the process of corrosion on confined surfaces.

“With the SFA, we can accurately determine the thickness of our metal film of interest and follow the development over time as corrosion proceeds,” says project scientist Kai Kristiansen.

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SemiconductorThe next generation of feature-filled and energy-efficient electronics will require computer chips just a few atoms thick. For all its positive attributes, trusty silicon can’t take us to these ultrathin extremes.

With two new semiconductors, however, it may be possible.

Electrical engineers have identified two semiconductors—hafnium diselenide and zirconium diselenide—that share or go beyond some of silicon’s desirable traits, starting with the fact that all three materials can “rust.”

“It’s a bit like rust, but a very desirable rust,” says Eric Pop, an associate professor of electrical engineering, who coauthored with postdoctoral scholar Michal Mleczko a paper on the research that appears in the journal Science Advances.

The new materials can also be shrunk to functional circuits just three atoms thick and they require less energy than silicon circuits. Although still experimental, the researchers say the materials could be a step toward the kinds of thinner, more energy-efficient chips demanded by devices of the future.

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Researchers have developed an inexpensive and scalable technique that can change plastic’s molecular structure to help it cast off heat.

Advanced plastics could usher in lighter, cheaper, more energy-efficient product components, including those used in vehicles, LEDs, and computers—if only they were better at dissipating heat.

The concept can likely be adapted to a variety of other plastics. In preliminary tests, it made a polymer about as thermally conductive as glass—still far less so than metals or ceramics, but six times better at dissipating heat than the same polymer without the treatment.

“Plastics are replacing metals and ceramics in many places, but they’re such poor heat conductors that nobody even considers them for applications that require heat to be dissipated efficiently,” says Jinsang Kim, a materials science and engineering professor at the University of Michigan. “We’re working to change that by applying thermal engineering to plastics in a way that hasn’t been done before.”

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GrapheneScientists have turned wood into an electrical conductor by making its surface graphene.

Chemist James Tour of Rice University and his colleagues used a laser to blacken a thin film pattern onto a block of pine. The pattern is laser-induced graphene (LIG), a form of the atom-thin carbon material discovered at Rice in 2014.

“It’s a union of the archaic with the newest nanomaterial into a single composite structure,” Tour says.

Previous iterations of LIG were made by heating the surface of a sheet of polyimide, an inexpensive plastic, with a laser. Rather than a flat sheet of hexagonal carbon atoms, LIG is a foam of graphene sheets with one edge attached to the underlying surface and chemically active edges exposed to the air.

Not just any polyimide would produce LIG, and some woods work better than others, Tour says. The research team tried birch and oak, but found that pine’s cross-linked lignocellulose structure made it better for the production of high-quality graphene than woods with a lower lignin content. Lignin is the complex organic polymer that forms rigid cell walls in wood.

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