Scientific studies describing the most basic processes often have the greatest impact in the long run. A new work by Rice University engineers could be one such, and it’s a gas, gas, gas for nanomaterials.
Rice materials theorist Boris Yakobson, graduate student Jincheng Lei and alumnus Yu Xie of Rice’s Brown School of Engineering have unveiled how a popular 2D material, molybdenum disulfide (MoS2), flashes into existence during chemical vapor deposition (CVD).
Knowing how the process works will give scientists and engineers a way to optimize the bulk manufacture of MoS2 and other valuable materials classed as transition metal dichalcogenides (TMDs), semiconducting crystals that are good bets to find a home in next-generation electronics.
Their study in the American Chemical Society journal ACS Nano focuses on MoS2’s “pre-history,” specifically what happens in a CVD furnace once all the solid ingredients are in place. CVD, often associated with graphene and carbon nanotubes, has been exploited to make a variety of 2D materials by providing solid precursors and catalysts that sublimate into gas and react. The chemistry dictates which molecules fall out of the gas and settle on a substrate, like copper or silicone, and assemble into a 2D crystal.
The problem has been that once the furnace cranks up, it’s impossible to see or measure the complicated chain of reactions in the chemical stew in real time.
“Hundreds of labs are cooking these TMDs, quite oblivious to the intricate transformations occurring in the dark oven,” said Yakobson, the Karl F. Hasselmann Professor of Materials Science and NanoEngineering and a professor of chemistry. “Here, we’re using quantum-chemical simulations and analysis to reveal what’s there, in the dark, that leads to synthesis.”
Yakobson’s theories often lead experimentalists to make his predictions come true. (For example, boron buckyballs.) This time, the Rice lab determined the path molybdenum oxide (MoO3) and sulfur powder take to deposit an atomically thin lattice onto a surface. More
Scientific studies describing the most basic processes often have the greatest impact in the long run. A new work by Rice University engineers could be one such, and it’s a gas, gas, gas for nanomaterials.
A new high-performance plastic foam developed from whey proteins can withstand extreme heat better than many common thermoplastics made from petroleum. A research team in Sweden reports that the material, which may be used for example in catalysts for cars, fuel filters or packaging foam, actually improves its mechanical performance after days of exposure to high temperatures.
Reporting in Advanced Sustainable Systems, researchers from KTH Royal Institute of Technology in Stockholm say the research opens the door to using protein-based foam materials in potentially tough environments, such as filtration, thermal insulation and fluid absorption.
The basic building blocks of the material are protein nanofibrils, or PNFs, which are self-assembled from hydrolyzed whey proteins — a product from cheese-processing — under specific temperature and pH conditions.
In tests the foams improved with aging. After one month of exposure to a temperature of 150C, the material became stiffer, tougher and stronger, says the study’s co-author, Mikael Hedenqvist , professor in the Division of Polymeric Materials at KTH.
“This material only gets stronger with time,” he says. “If we compare with petroleum-based, commercial foam materials made of polyethylene and polystyrene, they melt instantly and decompose under the same harsh conditions.”
Proteins are often water-soluble, which poses a challenge when developing protein-based materials. Despite this, the material proved water-resistant after the aging process, which polymerized the protein, creating new covalent bonds that stabilized the foams. The foam also resisted even more aggressive substances — such as surfactants and reducing agents — that normally decompose or dissolve proteins. The crosslinking also made the foam unaffected by diesel fuel or hot oil.
The material also showed better fire resistance than commonly used polyurethane thermoset.
“This biodegradable, sustainable material can be a viable option for use in aggressive environments where fire resistance is important,” Hedenqvist says.
Potential applications include providing support for catalytic metals that operate at higher temperatures, such as platinum catalysts for automobiles. The material could conceivably work as a fuel filter, too.
Other possibilities are to use it as packaging foam and in applications for sound and thermal insulation where higher temperatures may occur and where there is a risk of an aggressive environment.
Materials provided by KTH, Royal Institute of Technology. Note: Content may be edited for style and length. More
Advancements in wearable technology are reshaping the way we live, work and play, and also how healthcare is delivered and received. Wearables that have weaved their way into everyday life include smart watches and wireless earphones, while in the healthcare setting, common devices include wearable injectors, electrocardiogram (ECG) monitoring patches, listening aids, and more.
A major pain point facing the use of these wearables is the issue of keeping these devices properly and conveniently powered. As the number of wearables one uses increases, the need to charge multiple batteries rises in tandem, consuming huge amounts of electricity. Many users find it cumbersome to charge numerous devices every day, and inconvenient service disruptions occur when batteries run out.
A research team, led by Associate Professor Jerald Yoo from the Department of Electrical and Computer Engineering and the N.1 Institute for Health at the National University of Singapore (NUS), has developed a solution to these problems. Their technology enables a single device, such as a mobile phone placed in the pocket, to wirelessly power other wearable devices on a user’s body, using the human body as a medium for power transmission. The team’s novel system has an added advantage — it can harvest unused energy from electronics in a typical home or office environment to power the wearables.
Their achievement was first published in the journal Nature Electronics on 10 June 2021. It is the first of its kind to be established among existing literature on electronic wearables.
Using the human body as a medium for energy transmission
To extend battery life and sustain fully autonomous — yet wireless — operations of wearable devices, power transmission and energy harvesting approaches are required. However, conventional approaches for powering up body area wearables are limited by the distance that power can be transmitted, the “path” the energy can travel without facing obstacles, and the stability of energy movement. As such, none of the current methods have been able to provide sustainable power to wearables placed around the entire human body.
The NUS team decided to turn the tables on these limitations by designing a receiver and transmitter system that uses the very obstacle in wireless powering — the human body — as a medium for power transmission and energy harvesting. Each receiver and transmitter contains a chip that is used as a springboard to extend coverage over the entire body.
A user just needs to place the transmitter on a single power source, such as the smart watch on a user’s wrist, while multiple receivers can be placed anywhere on the person’s body. The system then harnesses energy from the source to power multiple wearables on the user’s body via a process termed as body-coupled power transmission. In this way, the user will only need to charge one device, and the rest of the gadgets that are worn can simultaneously be powered up from that single source. The team’s experiments showed that their system allows a single power source that is fully charged to power up to 10 wearable devices on the body, for a duration of over 10 hours.
As a complementary source of power, the NUS team also looked into harvesting energy from the environment. Their research found that typical office and home environments have parasitic electromagnetic (EM) waves that people are exposed to all the time, for instance, from a running laptop. The team’s novel receiver scavenges the EM waves from the ambient environment, and through a process referred to as body-coupled powering, the human body is able to harvest this energy to power the wearable devices, regardless of their locations around the body.
Paving the way for smaller, battery-less wearables
On the benefits of his team’s method, Assoc Prof Yoo said, “Batteries are among the most expensive components in wearable devices, and they add bulk to the design. Our unique system has the potential to omit the need for batteries, thereby enabling manufacturers to miniaturise the gadgets while reducing production cost significantly. More excitingly, without the constraints of batteries, our development can enable the next generation wearable applications, such as ECG patches, gaming accessories, and remote diagnostics.”
The NUS team will continue to enhance the powering efficiency of their transmitter/receiver system, with hopes that in future, any given power-transmitting device, be it a user’s mobile phone or smart watch, can satisfy the network power demands of all other wearables on the body, thus enabling a longer battery lifetime. More
Researchers at University of California San Diego School of Medicine used an artificial intelligence (AI) algorithm to sift through terabytes of gene expression data — which genes are “on” or “off” during infection — to look for shared patterns in patients with past pandemic viral infections, including SARS, MERS and swine flu.
Two telltale signatures emerged from the study, published June 11, 2021 in eBiomedicine. One, a set of 166 genes, reveals how the human immune system responds to viral infections. A second set of 20 signature genes predicts the severity of a patient’s disease. For example, the need to hospitalize or use a mechanical ventilator. The algorithm’s utility was validated using lung tissues collected at autopsies from deceased patients with COVID-19 and animal models of the infection.
“These viral pandemic-associated signatures tell us how a person’s immune system responds to a viral infection and how severe it might get, and that gives us a map for this and future pandemics,” said Pradipta Ghosh, MD, professor of cellular and molecular medicine at UC San Diego School of Medicine and Moores Cancer Center.
Ghosh co-led the study with Debashis Sahoo, PhD, assistant professor of pediatrics at UC San Diego School of Medicine and of computer science and engineering at Jacobs School of Engineering, and Soumita Das, PhD, associate professor of pathology at UC San Diego School of Medicine.
During a viral infection, the immune system releases small proteins called cytokines into the blood. These proteins guide immune cells to the site of infection to help get rid of the infection. Sometimes, though, the body releases too many cytokines, creating a runaway immune system that attacks its own healthy tissue. This mishap, known as a cytokine storm, is believed to be one of the reasons some virally infected patients, including some with the common flu, succumb to the infection while others do not.
But the nature, extent and source of fatal cytokine storms, who is at greatest risk and how it might best be treated have long been unclear. More
The demand for flexible wearable electronics has spiked with the dramatic growth of smart devices that can exchange data with other devices over the internet with embedded sensors, software, and other technologies. Researchers consequently have focused on exploring flexible energy storage devices, such as flexible supercapacitators (FSCs), that are lightweight and safe and easily integrate with other devices. FSCs have high power density and fast charge and discharge rates.
Printing electronics, manufacturing electronics devices and systems by using conventional printing techniques, has proved to be an economical, simple, and scalable strategy for fabricating FSCs. Traditional micromanufacturing techniques can be expensive and complex.
In Applied Physics Reviews, by AIP Publishing, researchers from Wuhan University and Hunan University provide a review of printed FSCs in terms of their ability to formulate functional inks, design printable electrodes, and integrate functions with other electronic devices.
Printed FSCs are generally manufactured by printing the functional inks on traditional organic and inorganic electrode materials on flexible substrates. Due to the thin film structure, these printed devices can be bent, stretched, and twisted to a certain radius without loss of electrochemical function.
In addition, the rigid current collector components of the supercapacitor can also be replaced by the flexible printed parts. Various printing techniques such as screen printing, inkjet printing, and 3D printing have been well established to fabricate the printed FSCs.
“The development of miniaturized, flexible, and planar high-performance electrochemical energy storage devices is an urgent requirement to promote the rapid development of portable electronic devices in daily life,” said author Wu Wei. “We can imagine that in the future, we can use any printer in our lives and can print a supercapacitator to charge a mobile phone or smart wristband at any time.”
The researchers found for printable ink formulations, two principles should be followed. First, when selecting ink components, it is vital to include fewer ineffective additives, better conductive binders, and excellent dispersion electrode materials. Second, the ink must have a suitable viscosity and a good rheology property to obtain excellent prints.
Printable functional materials, such as graphene and pseudocapacitive materials, are good core components of printed supercapacitators.
Since printed electronics offer the advantage of flexibility and low cost, they can be used to manufacture solar cells, flexible OLED displays, transistors, RFID tags, and other integrated smart devices. This opens up the possibility of many other applications, including smart textiles, intelligent packaging, and smart labels.
Materials provided by American Institute of Physics. Note: Content may be edited for style and length. More
Small pieces of plastic are everywhere, stretching from urban environments to pristine wilderness. Left to their own devices, it can take hundreds of years for them to degrade completely. Catalysts activated by sunlight could speed up the process, but getting these compounds to interact with microplastics is difficult. In a proof-of-concept study, researchers reporting in ACS Applied Materials & Interfaces developed self-propelled microrobots that can swim, attach to plastics and break them down.
While plastic products are omnipresent indoors, plastic waste and broken bits now litter the outdoors, too. The smallest of these — microplastics less than 5 mm in size — are hard to pick up and remove. In addition, they can adsorb heavy metals and pollutants, potentially harming humans or animals if accidentally consumed. So, previous researchers proposed a low-energy way to get rid of plastics in the environment by using catalysts that use sunlight to produce highly reactive compounds that break down these types of polymers. However, getting the catalysts and tiny plastic pieces in contact with each other is challenging and usually requires pretreatments or bulky mechanical stirrers, which aren’t easily scaled-up. Martin Pumera and colleagues wanted to create a sunlight-propelled catalyst that moves toward and latches onto microparticles and dismantles them.
To transform a catalytic material into light-driven microrobots, the researchers made star-shaped particles of bismuth vanadate and then evenly coated the 4-8 ?m-wide structures with magnetic iron oxide. The microrobots could swim down a maze of channels and interact with microplastic pieces along their entire lengths. The researchers found that under visible light, microrobots strongly glommed on to four common types of plastics. The team then illuminated pieces of the four plastics covered with the microrobot catalyst for seven days in a dilute hydrogen peroxide solution. They observed that the plastic lost 3% of its weight and that the surface texture for all types changed from smooth to pitted, and small molecules and components of the plastics were found in the left-over solution. The researchers say the self-propelled microrobot catalysts pave the way toward systems that can capture and degrade microplastics in hard-to-reach-locations.
Materials provided by American Chemical Society. Note: Content may be edited for style and length. More
On Earth right now, there are about 10 trillion gigabytes of digital data, and every day, humans produce emails, photos, tweets, and other digital files that add up to another 2.5 million gigabytes of data. Much of this data is stored in enormous facilities known as exabyte data centers (an exabyte is 1 billion gigabytes), which can be the size of several football fields and cost around $1 billion to build and maintain.
Many scientists believe that an alternative solution lies in the molecule that contains our genetic information: DNA, which evolved to store massive quantities of information at very high density. A coffee mug full of DNA could theoretically store all of the world’s data, says Mark Bathe, an MIT professor of biological engineering.
“We need new solutions for storing these massive amounts of data that the world is accumulating, especially the archival data,” says Bathe, who is also an associate member of the Broad Institute of MIT and Harvard. “DNA is a thousandfold denser than even flash memory, and another property that’s interesting is that once you make the DNA polymer, it doesn’t consume any energy. You can write the DNA and then store it forever.”
Scientists have already demonstrated that they can encode images and pages of text as DNA. However, an easy way to pick out the desired file from a mixture of many pieces of DNA will also be needed. Bathe and his colleagues have now demonstrated one way to do that, by encapsulating each data file into a 6-micrometer particle of silica, which is labeled with short DNA sequences that reveal the contents.
Using this approach, the researchers demonstrated that they could accurately pull out individual images stored as DNA sequences from a set of 20 images. Given the number of possible labels that could be used, this approach could scale up to 1020 files.
Bathe is the senior author of the study, which appears today in Nature Materials. The lead authors of the paper are MIT senior postdoc James Banal, former MIT research associate Tyson Shepherd, and MIT graduate student Joseph Berleant. More
The 30,000 or so genes making up the human genome contain the instructions vital to life. Yet each of our cells expresses only a subset of these genes in their daily functioning. The difference between a heart cell and a liver cell, for example, is determined by which genes are expressed — and the correct expression of genes can mean the difference between health and disease.
Until recently, researchers investigating the genes underlying disease have been limited because traditional imaging techniques only allow for the study of a handful of genes at a time.
A new technique developed by Jun Hee Lee, Ph.D., and his team at the University of Michigan Medical School, part of Michigan Medicine, uses high-throughput sequencing, instead of a microscope, to obtain ultra-high-resolution images of gene expression from a tissue slide. The technology, which they call Seq-Scope, enables a researcher to see every gene expressed, as well single cells and structures within those cells, at incredibly high resolution: 0.6 micrometers or 66 times smaller than a human hair — beating current methods by multiple orders of magnitude.
“Whenever a pathologist gets a tissue sample, they stain it and look at it under the microscope — it’s how they diagnose disease,” explained Lee, an associate professor in the Department of Molecular & Integrative Physiology. “Instead of doing that, with our new method, we have made a microdevice that you can overlay with a tissue sample and sequence everything within it with a barcode with spatial coordinates.”
Each so-called barcode is made up of a nucleotide sequence — the pattern of A, T, G, an C — found in DNA. Using these barcodes, a computer is able to locate every gene within a tissue sample, creating a Google-like database of all of the mRNAs transcribed from the genome.
“People have been trying to do this with other methods, such as microprinting, microbeads or microfluidic devices, but because of technological limitations, their resolution has been a distance of 20-100 micrometers. At that resolution you can’t really see the level of detail needed to diagnose diseases,” Lee said.
Lee adds that the technology has the potential to create an unbiased systematic way to analyze genes.
“Whenever we do science, we had to make a hypothesis about the role of two or three genes, but now we have genome-wide data at the microscopic scale and much more knowledge about what’s going on inside that patient or model animal’s tissue.”
This knowledge could be used to provide insight into why certain patients respond to certain drugs while others do not, said Lee.
The team demonstrated the effectiveness of the technique using normal and diseased liver cells, successfully identifying dying liver cells, their surrounding inflamed immune cells and liver cells with altered gene expression.
“This technology actually showed many known pathological features that people have previously discovered but also many genes that are regulated in a novel way that was unrecognized previously,” said Lee. “Seq-Scope technology, combined with other single cell RNA sequencing techniques, could accelerate scientific discoveries and might lead to a new paradigm in molecular diagnosis.”
Materials provided by Michigan Medicine – University of Michigan. Original written by Kelly Malcom. Note: Content may be edited for style and length. More