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Category: nanotechnology – Page 131

Because of their unique physical, photonic, thermal, and electronic capabilities, two-dimensional (2D) nanostructures have exhibited tremendous promise in the domains of bioengineering, sensing, and energy storage.

Study: Two Dimensional Silicene Nanosheets: A New Choice of Electrode Material for High-Performance Supercapacitor. Image Credit: Quardia/Shutterstock.com.

Nonetheless, combining silicon-based nanomaterials into high-performance power storage systems remains a largely undeveloped subject because of the complex manufacturing process. New work published in the journal ACS Applied Materials & Interfaces hope to address this problem by effectively integrating silicene nanosheets into a high-voltage supercapacitor.

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Researchers from Linköping University and the Royal Institute of Technology in Sweden have proposed a new device concept that can efficiently transfer the information carried by electron spin to light at room temperature—a stepping stone toward future information technology. They present their approach in an article in Nature Communications.

Light and electron charge are the main media for information processing and transfer. In the search for information technology that is even faster, smaller and more energy-efficient, scientists around the globe are exploring another property of —their spin. Electronics that exploit both the spin and the charge of the electron are called “spintronics.”

Like the Earth, an electron spins around its own axis, either clockwise or counterclockwise. The handedness of the rotation is referred to as spin-up and spin-down states. In spintronics, the two states represent the binary bits and thus carry information. The information encoded by these can be converted by a -emitting device into light, which then carries the information over a long distance through fiber optics. The transfer of quantum information opens the possibility to exploit both and light, and the interaction between them, a technology known as “opto-spintronics.”

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In recent years, electronics and chemical engineers have devised different chemical doping techniques to control the sign and concentration of charge carriers in different material samples. Chemical doping methods essentially entail introducing impurities into materials or substances to change their electrical properties.

These promising methods have been successfully applied on several materials including van der Waals (vdW) materials. VdW materials are structures characterized by strongly bonded 2D layers, which are bound in the third dimension through weaker dispersion forces.

Researchers at University of California, Berkeley (UC Berkeley), the Kavli Energy Nanosciences Institute, Beijing Institute of Technology, Shenzhen University, Tsinghua University recently introduced a new tunable and reversible approach to chemically dope graphene. Their approach, introduced in a paper published in Nature Electronics, is based on laser-assisted chlorination.

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What goes on inside planets like Neptune and Uranus? To find out, an international team headed by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the University of Rostock and France’s École Polytechnique conducted a novel experiment. They fired a laser at a thin film of simple PET plastic and investigated what happened using intensive laser flashes. One result was that the researchers were able to confirm their earlier thesis that it really does rain diamonds inside the ice giants at the periphery of our solar system. And another was that this method could establish a new way of producing nanodiamonds, which are needed, for example, for highly-sensitive quantum sensors. The group has presented its findings in the journal Science Advances.

The conditions in the interior of icy giant planets like Neptune and Uranus are extreme: temperatures reach several thousand degrees Celsius, and the pressure is millions of times greater than in the Earth’s atmosphere. Nonetheless, states like this can be simulated briefly in the lab: powerful laser flashes hit a film-like material sample, heat it up to 6,000 degrees Celsius for the blink of an eye and generate a shock wave that compresses the material for a few nanoseconds to a million times the atmospheric pressure.

“Up to now, we used hydrocarbon films for these kinds of experiment,” explains Dominik Kraus, physicist at HZDR and professor at the University of Rostock. “And we discovered that this produced tiny diamonds, known as nanodiamonds.”

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Breakthroughs in modern microelectronics depend on understanding and manipulating the movement of electrons in metal. Reducing the thickness of metal sheets to the order of nanometers can enable exquisite control over how the metal’s electrons move. By doing so, one can impart properties that aren’t seen in bulk metals, such as ultrafast conduction of electricity. Now, researchers from Osaka University and collaborating partners have synthesized a novel class of nanostructured superlattices. This study enables an unusually high degree of control over the movement of electrons within metal semiconductors, which promises to enhance the functionality of everyday technologies.

Precisely tuning the architecture of metal nanosheets, and thus facilitating advanced microelectronic functionalities, remains an ongoing line of work worldwide. In fact, several Nobel prizes have been awarded on this topic. Researchers conventionally synthesize nanostructured superlattices—regularly alternating layers of metals, sandwiched together—from materials of the same dimension; for example, sandwiched 2D sheets. A key aspect of the present researchers’ work is its facile fabrication of hetero-dimensional superlattices; for example, 1D nanoparticle chains sandwiched within 2D nanosheets.

“Nanoscale hetero-dimensional superlattices are typically challenging to prepare, but can exhibit valuable physical properties, such as anisotropic electrical conductivity,” explains Yung-Chang Lin, senior author. “We developed a versatile means of preparing such structures, and in so doing we will inspire synthesis of a wide range of custom superstructures.”

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The new research provides a more complete picture of how diamond rain forms on other planets.

Researchers have discovered that “diamond rain,” unique precipitation that has long been speculated to occur on icy giant planets, may occur more frequently than previously believed.

To learn more about the circumstances on the icy giant planets Neptune and Uranus, a group of researchers from Germany and France has created an intriguing experiment, according to an article published by Physic.org on Friday.

A team of researchers have discovered that “diamond rain,” unique precipitation that has long been speculated to occur on ice giant planets, may occur more frequently than previously believed.

Continue reading “Scientists create nanodiamonds from plastic bottles” | >

“We don’t need any energy input, and it bubbles hydrogen like crazy. I’ve never seen anything like it,” said UCSC Professor Scott Oliver, describing a new aluminum-gallium nanoparticle powder that generates H2 when placed in water – even seawater.

Aluminum by itself rapidly oxidizes in water, stripping the O out of H2O and releasing hydrogen as a byproduct. This is a short-lived reaction though, because in most cases the metal quickly attains a microscopically thin coating of aluminum oxide that seals it off and puts an end to the fun.

But chemistry researchers at UC Santa Cruz say they’ve found a cost-effective way to keep the ball rolling. Gallium has long been known to remove the aluminum oxide coating and keep the aluminum in contact with water to continue the reaction, but previous research had found that aluminum-heavy combinations had a limited effect.

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The skin is one of the largest and most accessible organs in the human body, but penetrating its deep layers for medicinal and cosmetic treatments still eludes science.

Although there are some remedies—such as nicotine patches to stop smoking—administered through the skin, this method of treatment is rare since the particles that penetrate must be no larger than 100 nanometers. Creating effective tools using such tiny particles is a great challenge. Because the particles are so small and difficult to see, it is equally challenging to determine their exact location inside the body—information necessary to ensure that they reach intended target tissue. Today such information is obtained through invasive, often painful, biopsies.

A novel approach, developed by researchers at Bar-Ilan University in Israel, provides an innovative solution to overcoming both of these challenges. Combining techniques in nanotechnology and optics, they produced tiny (nanometric) diamond particles so small that they are capable of penetrating skin to deliver medicinal and cosmetic remedies. In addition, they created a safe, laser-based optical method that quantifies nanodiamond penetration into the various layers of the skin and determines their location and concentration within body tissue in a non-invasive manner—eliminating the need for a biopsy.

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Composite particles with submicron sizes can be produced by irradiating a suspension of nanoparticles with a laser beam. Violent physical and chemical processes take place during irradiation, many of which have been poorly understood to date. Recently completed experiments, carried out at the Institute of Nuclear Physics of the Polish Academy of Sciences in Cracow, have shed new light on some of these puzzles.

When a strikes agglomerates of nanoparticles suspended in a colloid, events occur that are as dramatic as they are useful. The tremendous increase in temperature leads to the melting together of nanoparticles into a composite particle. A thin layer of liquid next to the heated material rapidly transforms into vapor, and whole sequences of chemical reactions take place under that change in fractions of a second. Using this method, called laser melting, scientists from the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow not only produced new nanocomposites, but also described some of the poorly understood processes responsible for their formation.

“The laser melting process itself, consisting of irradiating particles of material in suspension with unfocused laser light, has been known for years. It is mainly used for the production of single component materials. We, as one of only two research teams in the world, are trying to use this technique to produce composite submicron particles. In this area, the field is still in its infancy, there are still many unknowns, hence our joy that some puzzles that perplexed us have just been unraveled,” says Dr. Żaneta Świątkowska-Warkocka, a professor at IFJ PAN, the co-author of a scientific article just published in the journal Scientific Reports.

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