In a breakthrough, scientists have used the humble soybean to make the world’s strongest material graphene commercially more viable.
Graphene is a carbon material that is one atom thick. Its thin composition and high conductivity means it is used in applications ranging from miniaturised electronics to biomedical devices.
These properties also enable thinner wire connections; providing extensive benefits for computers, solar panels, batteries, sensors and other devices.
Until now, the high cost of graphene production has been the major roadblock in its commercialisation. Previously, graphene was grown in a highly-controlled environment with explosive compressed gases, requiring long hours of operation at high temperatures and extensive vacuum processing.
Scientists at Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia have developed a novel “GraphAir” technology which eliminates the need for such a highly-controlled environment.
“This ambient-air process for graphene fabrication is fast, simple, safe, potentially scalable, and integration friendly”, CSIRO scientist Zhao Jun Han, said. “Our unique technology is expected to reduce the cost of graphene production and improve the uptake in new applications,” Han said.
GraphAir transforms soybean oil – a renewable, natural material – into graphene films in a single step.
“Our GraphAir technology results in good and transformable graphene properties, comparable to graphene made by conventional methods,” CSIRO scientist Dong Han Seo said.
With heat, soybean oil breaks down into a range of carbon building units that are essential for the synthesis of graphene. The team also transformed other types of renewable and even waste oil, such as those leftover from barbecues or cooking, into graphene films.
The potential applications of graphene include water filtration and purification, renewable energy, sensors, personalised healthcare and medicine, to name a few. Graphene has excellent electronic, mechanical, thermal and optical properties as well. Its uses range from improving battery performance in energy devices, to cheaper solar panels.
The research was published in the journal Nature Communications.
By: Gadgets360, India
Source: gadgets.ndtv.comRead More
Harvard scientists report they have succeeded in creating the rarest material on the planet— atomic metallic hydrogen.
Thomas D. Cabot Professor of the Natural Sciences Isaac Silvera and postdoctoral fellow Ranga Dias, have begun to answer some fundamental questions about the nature of matter with the material, which is believed to have a number of applications, including as a room-temperature superconductor.
“This is the Holy Grail of high-pressure physics,” Silvera said in a statement. “It’s the first-ever sample of metallic hydrogen on Earth, so when you’re looking at it, you’re looking at something that’s never existed before.”
Silvera and Dias were able to squeeze a tiny hydrogen sample at 495 gigapascal (GPa) or more than 71.7 million pounds per square inch, which is greater than the pressure at the center of the Earth.
According to Silvera, at such extreme pressures solid molecular hydrogen, which consists of molecules on the lattice sites of the solid, breaks down and the tightly bound molecules dissociate to transform into atomic hydrogen.
In the experiment, the two researchers used two small pieces of carefully polished synthetic diamond and treated them to make them even tougher. They then mounted them opposite each other in a device called a diamond anvil cell.
“Diamonds are polished with diamond powder and that can gouge out carbon from the surface,” Silvera said. “When we looked at the diamond using atomic force microscopy, we found defects, which could cause it to weaken and break.”
They were able to use a reactive ion etching process to shave a tiny layer—just five microns thick—from the diamond’s surface and then coated the diamond with a thin layer of alumina to prevent the hydrogen from diffusing into the crystal structure and embrittling it.
Silvera said the discovery could lead to new materials.
“One prediction that’s very important is metallic hydrogen is predicted to be meta-stable,” Silvera said. “That means if you take the pressure off, it will stay metallic, similar to the way diamonds form from graphite under intense heat and pressure, but remain diamonds when that pressure and heat are removed.”
Silvera said understanding whether the material is stable could suggest that metallic hydrogen could act as a superconductor at room temperatures.
“As much as 15 percent of energy is lost to dissipation during transmission,” he said, “so if you could make wires from this material and use them in the electrical grid, it could change that story.”
Dias explained that a room temperature superconductor could change the transportation system by making magnetic levitation of high-speed trains possible, as well as making electric cars more efficient and improving the performance of many electronic devices.
Other applications for the material could provide major improvements in energy production and storage, because superconductors have zero resistance, making superconducting coils more useful to store excess energy, which could then be used whenever it is needed.
Another application could be as a more powerful rocket propellant.
“It takes a tremendous amount of energy to make metallic hydrogen,” Silvera said. “And if you convert it back to molecular hydrogen, all that energy is released, so that would make it the most powerful rocket propellant known to man, and could revolutionize rocketry.”
Fuels are often measured by a specific impulse—a measure in seconds of how fast a propellant is fired from the back of the rocket.
The most powerful fuels in use today have a specific impulse of about 450 seconds, while the specific impulse for metallic hydrogen is theorized to be 1,700 seconds.
“That would easily allow you to explore the outer planets,” Silvera said. “We would be able to put rockets into orbit with only one stage, versus two and could send up larger payloads, so it could be very important.”
The study was published in Science.
While the Harvard scientists believe they have made the breakthrough that researchers have been trying to discover for several decades, others aren’t so sure.
In a recent article published in Nature, five experts reported doubt on the discovery of metallic hydrogen, saying that the accompanying paper is not convincing.
By: R&D magazine, USA
Source: www.rdmag.comRead More
A prototype device to detect the scent of disease
ONE of a doctor’s most valuable tools is his nose. Since ancient times, medics have relied on their sense of smell to help them work out what is wrong with their patients. Fruity odours on the breath, for example, let them monitor the condition of diabetics. Foul ones assist the diagnosis of respiratory-tract infections.
But doctors can, as it were, smell only what they can smell—and many compounds characteristic of disease are odourless. To deal with this limitation Hossam Haick, a chemical engineer at the Technion Israel Institute of Technology, in Haifa, has developed a device which, he claims, can do work that the human nose cannot.
The idea behind Dr Haick’s invention is not new. Many diagnostic “breathalysers” already exist, and sniffer dogs, too, can be trained to detect illnesses such as cancer. Most of these approaches, though, are disease-specific. Dr Haick wanted to generalise the process.
As he describes in ACS Nano, he and his colleagues created an array of electrodes made of carbon nanotubes (hollow, cylindrical sheets of carbon atoms) and tiny particles of gold. Each of these had one of 20 organic films laid over it. Each film was sensitive to one of a score of compounds known to be found on the breath of patients suffering from a range of 17 illnesses, including Parkinson’s disease, multiple sclerosis, bladder cancer, pulmonary hypertension and Crohn’s disease. When a film reacted, its electrical resistance changed in a predictable manner. The combined changes generated an electrical fingerprint that, the researchers hoped, would be diagnostic of the disease a patient was suffering from.
To test their invention, Dr Haick and his colleagues collected 2,808 breath samples from 1,404 patients who were suffering from at least one of the diseases they were looking at. Its success varied. It could distinguish between samples from patients suffering from gastric cancer and bladder cancer only 64% of the time. At distinguishing lung cancer from head and neck cancer it was, though, 100% successful. Overall, it got things right 86% of the time. Not perfect, then, but a useful aid to a doctor planning to conduct further investigations. And this is only a prototype. Tweaked, its success rate would be expected to improve.Read More