North Carolina State University

North Carolina State University, officially North Carolina State University at Raleigh, is a public, coeducational, research university located in Raleigh, North Carolina, United States.

A new way to capture heat and turn it into electricity

Scientists find new way to capture heat that otherwise would have been lost An international team of scientists has figured out how to capture heat and turn it into electricity. The discovery, published last week in the journal Science Advances, could create more efficient energy generation from heat in things like car exhaust, interplanetary space probes

A new way to capture heat and turn it into electricity

Better repair of sun and age-damaged skin?

In the future, you could be your very own fountain of youth – or at least your own skin repair reservoir. In a proof-of-concept study, researchers from North Carolina State University have shown that exosomes harvested from human skin cells are more effective at repairing sun-damaged skin cells in mice than popular retinol or stem

Better repair of sun and age-damaged skin?

A device that is not quite a robot and not quite a computer but has characteristics of both

Inspired by octopuses, researchers have developed a structure that senses, computes and responds without any centralized processing – creating a device that is not quite a robot and not quite a computer, but has characteristics of both. The new technology holds promise for use in a variety of applications, from soft robotics to prosthetic devices.

A device that is not quite a robot and not quite a computer but has characteristics of both

Drug-resistant pathogens meet their match with a self-sterilizing polymer

Researchers from North Carolina State University have found that an elastic polymer possesses broad-spectrum antimicrobial properties, allowing it to kill a range of viruses and drug-resistant bacteria in just minutes – including methicillin-resistant Staphylococcus aureus (MRSA). “We were exploring a different approach for creating antimicrobial materials when we observed some interesting behavior from this polymer

Drug-resistant pathogens meet their match with a self-sterilizing polymer

Using light and magnetic fields to reconfigure soft robots into new shapes

Researchers from North Carolina State University and Elon University have developed a technique that allows them to remotely control the movement of soft robots, lock them into position for as long as needed and later reconfigure the robots into new shapes. The technique relies on light and magnetic fields. “We’re particularly excited about the reconfigurability,”

Using light and magnetic fields to reconfigure soft robots into new shapes

Creating multi-junction solar cells from inexpensive off-the-shelf components

Multi-junction solar cells are both the most efficient type of solar cell on the market today and the most expensive type of solar cell to produce. In a proof-of-concept paper, researchers from North Carolina State University detail a new approach for creating multi-junction solar cells using off-the-shelf components, resulting in lower cost, high-efficiency solar cells

Creating multi-junction solar cells from inexpensive off-the-shelf components

It’s Here: Salmonella resistant to antibiotics of last resort

Researchers from North Carolina State University have found a gene that gives Salmonella resistance to antibiotics of last resort in a sample taken from a human patient in the U.S. The find is the first evidence that the gene mcr-3.1 has made its way into the U.S. from Asia. There are more than 2,500 known serotypes of Salmonella. In the

It’s Here: Salmonella resistant to antibiotics of last resort

Developing fast on-site plant disease detection tools

Researchers have developed a new technique that uses microneedle patches to collect DNA from plant tissues in one minute, rather than the hours needed for conventional techniques. DNA extraction is the first step in identifying plant diseases, and the new method holds promise for the development of on-site plant disease detection tools. “When farmers detect

Developing fast on-site plant disease detection tools

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New interface for electronics: Soft and stretchable fibers that can detect touch, as well as strain and twisting

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Researchers from North Carolina State University have created elastic, touch-sensitive fibers that can interface with electronic devices.

“Touch is a common way to interact with electronics using keyboards and touch screens,” says Michael Dickey, a professor of chemical and biomolecular engineering at NC State and corresponding author of a paper describing the work. “We have created soft and stretchable fibers that can detect touch, as well as strain and twisting. These microscopic fibers may be useful for integrating electronics in new places, including wearable devices.”

The new fibers are made of tube-like polymer strands that contain a liquid metal alloy, eutectic gallium and indium (EGaIn). The strands are only a few hundred microns in diameter, which is slightly thicker than a human hair.

Each fiber consists of three strands. One is completely filled with EGaIn, one is two-thirds filled with EGaIn, and one is only one-third filled with EGaIn. The slim tubes are then twisted together into a tight spiral.

The touch-responsive fiber works because of capacitance, or the phenomenon in which electric charge is stored between two conductors separated by an insulator. For example, when your finger (which is a conductor) touches the screen of your smartphone (which is an insulator), it changes the capacitance between your finger and the electronic material beneath the screen. The smartphone’s technology then interprets that change in capacitance as a command to open an app or to type on the keypad.

Similarly, when your finger touches the elastic fiber, it changes the capacitance between your finger and the EGaIn inside the insulating polymer strands. By moving your finger along the fiber, the capacitance will vary, depending on how many of the strands contain EGaIn at that point in the fiber.

This effectively gives you the ability to send different electronic signals depending on which part of the fiber you touch.

The researchers also developed a sensor using two polymer strands, both of which are completely filled with EGaIn.

Again, the strands are twisted into a tight spiral. Increasing the number of twists elongates the elastic strands and brings the EGaIn in the two tubes closer together. This changes the capacitance between the two strands.

“We can tell how many times the fiber has been twisted based on the change in capacitance,” Dickey says. “That’s valuable for use in torsion sensors, which measure how many times, and how quickly, something revolves. The advantage of our sensor is that it is built from elastic materials and can therefore be twisted 100 times more – two orders of magnitude – than existing torsion sensors.”

Learn more: Touch-Sensitive, Elastic Fibers Offer New Interface for Electronics

 

 

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Rice makes light-driven nanosubmarines

Rice University scientists have created light-driven, single-molecule submersibles that contain just 244 atoms. Illustration by Loïc Samuel

Rice University scientists have created light-driven, single-molecule submersibles that contain just 244 atoms. Illustration by Loïc Samuelhough they’re not quite ready for boarding a lá “Fantastic Voyage,” nanoscale submarines created at Rice University are proving themselves seaworthy.

Each of the single-molecule, 244-atom submersibles built in the Rice lab of chemist James Tour has a motor powered by ultraviolet light. With each full revolution, the motor’s tail-like propeller moves the sub forward 18 nanometers.

And with the motors running at more than a million RPM, that translates into speed. Though the sub’s top speed amounts to less than 1 inch per second, Tour said that’s a breakneck pace on the molecular scale.

“These are the fastest-moving molecules ever seen in solution,” he said.

Expressed in a different way, the researchers reported this month in the American Chemical Society journal Nano Letters that their light-driven nanosubmersibles show an “enhancement in diffusion” of 26 percent. That means the subs diffuse, or spread out, much faster than they already do due to Brownian motion, the random way particles spread in a solution.

While they can’t be steered yet, the study proves molecular motors are powerful enough to drive the sub-10-nanometer subs through solutions of moving molecules of about the same size.

“This is akin to a person walking across a basketball court with 1,000 people throwing basketballs at him,” Tour said.

Tour’s group has extensive experience with molecular machines. A decade ago, his lab introduced the world to nanocars, single-molecule cars with four wheels, axles and independent suspensions that could be “driven” across a surface.

Tour said many scientists have created microscopic machines with motors over the years, but most have either used or generated toxic chemicals. He said a motor that was conceived in the last decade by a group in the Netherlands proved suitable for Rice’s submersibles, which were produced in a 20-step chemical synthesis.

“These motors are well-known and used for different things,” said lead author and Rice graduate student Victor García-López. “But we were the first ones to propose they can be used to propel nanocars and now submersibles.”

The motors, which operate more like a bacteria’s flagellum than a propeller, complete each revolution in four steps. When excited by light, the double bond that holds the rotor to the body becomes a single bond, allowing it to rotate a quarter step. As the motor seeks to return to a lower energy state, it jumps adjacent atoms for another quarter turn. The process repeats as long as the light is on.

For comparison tests, the lab also made submersibles with no motors, slow motors and motors that paddle back and forth. All versions of the submersibles have pontoons that fluoresce red when excited by a laser, according to the researchers. (Yellow, sadly, was not an option.)

“One of the challenges was arming the motors with the appropriate fluorophores for tracking without altering the fast rotation,” García-López said.

Once built, the team turned to Gufeng Wang at North Carolina State University to measure how well the nanosubs moved.

“We had used scanning tunneling microscopy and fluorescence microscopy to watch our cars drive, but that wouldn’t work for the submersibles,” Tour said. “They would drift out of focus pretty quickly.”

The North Carolina team sandwiched a drop of diluted acetonitrile liquid containing a few nanosubs between two slides and used a custom confocal fluorescence microscope to hit it from opposite sides with both ultraviolet light (for the motor) and a red laser (for the pontoons).

The microscope’s laser defined a column of light in the solution within which tracking occurred, García-López said. “That way, the NC State team could guarantee it was analyzing only one molecule at a time,” he said.

Rice’s researchers hope future nanosubs will be able to carry cargoes for medical and other purposes. “There’s a path forward,” García-López said. “This is the first step, and we’ve proven the concept. Now we need to explore opportunities and potential applications.”

Read more: Rice makes light-driven nanosubmarines

 

 

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Antibiotic Smart Bomb Can Target Specific Strains of Bacteria

Researchers have developed a technique to selectively remove specific strains of bacteria.

The technique offers a potential approach to treat infections by multi-drug resistant bacteria.

Researchers from North Carolina State University have developed a de facto antibiotic “smart bomb” that can identify specific strains of bacteria and sever their DNA, eliminating the infection. The technique offers a potential approach to treat infections by multi-drug resistant bacteria.

“Conventional antibiotic treatments kill both ‘good’ and ‘bad’ bacteria, leading to unintended consequences, such as opportunistic infections,” says Dr. Chase Beisel, an assistant professor of chemical and biomolecular engineering at NC State and senior author of a paper describing the work. “What we’ve shown in this new work is that it is possible to selectively remove specific strains of bacteria without affecting populations of good bacteria.”

The new approach works by taking advantage of a part of an immune system present in many bacteria called the CRISPR-Cas system. The CRISPR-Cas system protects bacteria from invaders such as viruses by creating small strands of RNA called CRISPR RNAs, which match DNA sequences specific to a given invader. When those CRISPR RNAs find a match, they unleash Cas proteins that cut the DNA.

The NC State researchers have demonstrated that designing CRISPR RNAs to target DNA sequences in the bacteria themselves causes bacterial suicide, as a bacterium’s CRISPR-Cas system attacks its own DNA.

“In lab testing, we found that this approach removes the targeted bacteria,” Beisel says. “We’re still trying to understand precisely how severing the DNA leads to elimination of the bacteria. However, we’re encouraged by the ease in specifically targeting different bacteria and the potency of elimination.”

The researchers tested the approach in controlled cultures with different combinations of bacteria present, and were able to eliminate only the targeted strain. “For example, we were able to eliminate Salmonella in a culture without affecting good bacteria normally found in the digestive tract,” Beisel says.

The researchers were also able to demonstrate the precision of the technique by eliminating one strain of a species, but not another strain of the same species which shares 99 percent of the same DNA.

Another benefit of the approach, Beisel says, is that “by targeting specific DNA strands through the CRISPR-Cas system, we’re able to bypass the mechanisms underlying the many examples of antibiotic resistance.”

The researchers are currently working to develop effective methods for delivering the CRISPR RNAs in clinical settings.

“This sets the stage for next-generation antibiotics using programmable CRISPR-Cas systems,” says Dr. Rodolphe Barrangou, an associate professor of food, bioprocessing and nutrition sciences at NC State and co-author of the manuscript.

Read more . . .

 

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Silver Nanowire Sensors Hold Promise for Prosthetics, Robotics

Silver-Sensor-Thumb-225

A sensor based on silver nanowires is mounted onto a thumb joint to monitor the skin strain associated with thumb flexing. The sensor shows good wearability and large-strain sensing capability. (Photo: Shanshan Yao.)

“These sensors could be used to help develop prosthetics that respond to a user’s movement and provide feedback when in use”

North Carolina State University researchers have used silver nanowires to develop wearable, multifunctional sensors that could be used in biomedical, military or athletic applications, including new prosthetics, robotic systems and flexible touch panels. The sensors can measure strain, pressure, human touch and bioelectronic signals such as electrocardiograms.

“The technology is based on either physical deformation or “fringing” electric field changes. The latter is very similar to the mechanism used in smartphone touch screens, but the sensors we’ve developed are stretchable and can be mounted on a variety of curvilinear surfaces such as human skin,” says Shanshan Yao, a Ph.D. student at NC State and lead author of a paper on the work.

“These sensors could be used to help develop prosthetics that respond to a user’s movement and provide feedback when in use,” says Dr. Yong Zhu, an associate professor of mechanical and aerospace engineering at NC State and senior author of the paper. “They could also be used to create robotics that can ‘feel’ their environment, or the sensors could be incorporated into clothing to track motion or monitor an individual’s physical health.”

The researchers built on Zhu’s earlier work to create highly conductive and elastic conductors made from silver nanowires. Specifically, the researchers sandwiched an insulating material between two of the stretchable conductors. The two layers then have the ability – called “capacitance” – to store electric charges. Pushing, pulling or touching the stretchable conductors changes the capacitance. The sensors work by measuring that change in capacitance.

“Creating these sensors is simple and low cost,” Yao says. “And we’ve already demonstrated the sensors in several prototype applications.”

For example, the researchers employed these sensors to monitor thumb movement, which can be useful in controlling robotic or prosthetic devices. The researchers also demonstrated an application to monitor knee movements while a test subject is running, walking and jumping.

“The deformation involved in these movements is large, and would break a lot of other sensor devices,” Zhu says. “But our sensors can be stretched to 150 percent or more of their original length without losing functionality, so they can handle it.”

The researchers also developed an array of sensors that can map pressure distribution, which is important for use in robotics and prosthetics applications. The sensors exhibit a quick response time – 40 milliseconds – so strain and pressure can be monitored in real time.

Read more . . .

 

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