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applied_physics (8)

Lamina Tenuissima...

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Illustration of a tungsten disulfide monolayer suspended in air and patterned with a square array of nanoholes. Upon laser excitation, the monolayer emits photoluminescence. A portion of this light couples into the monolayer and is guided along the material. At the nanohole array, periodic modulation in the refractive index causes a small portion of the light to decay out of the plane of the material, allowing the light to be observed as guided mode resonance. Courtesy: E Cubukcu, UCSD

 

Note: lamina tenuissima = thinnest (Latin)

Topics: Applied Physics, Nanotechnology, Optical Physics, Photonics


Researchers have succeeded in making the thinnest ever optical device in the form of a waveguide just three atomic layers thick. The device could lead to the development of higher density optoelectronic chips.

Optical waveguides are crucial components in data communication technologies but scaling them down to the nanoscale has proved to be no easy task, despite important advances in nano-optics and nanomaterials. Indeed, the thinnest waveguide used in commercial applications today is hundreds of nanometres thick and researchers are studying nanowire waveguides down to 50 nm in the laboratory.

“We have now pushed this limit down to just three atoms thick,” says Ertugrul Cubukcu of the University of California at San Diego, who led this new research effort. “Such a thin waveguide, which is at the ultimate limit for how thin an optical waveguide can be built, might potentially lead to a higher density of waveguides or optical elements on an optoelectronic chip – in the same way that ever smaller transistors have led to a higher density of these devices on an electronic chip.”

Cubukcu and colleagues’ waveguide is just six angstroms thick. This makes it 104 times thinner than a typical optical fiber and about 500 times thinner than on-chip optical waveguides in integrated photonic circuits.

 

Three-atom-thick optical waveguide is the thinnest ever, Belle Dumé, Physics World

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Cyclocarbon...

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From left to right, precursor molecule C24O6, intermediates C22O4 and C20O2 and the final product cyclo [18]carbon C18 created on surface by dissociating CO masking groups using atom manipulation. The bottom row shows atomic force microscopy (AFM) data using a CO functionalized tip. Credit: IBM Research

 

Topics: Applied Physics, Atomic Force Microscopy, Chemistry, Nanotechnology, Research


A team of researchers from Oxford University and IBM Research has for the first time successfully synthesized the ring-shaped multi-carbon compound cyclocarbon. In their paper published in the journal Science, the group describes the process they used and what they learned about the bonds that hold a cyclocarbon together.

Carbon is one of the most abundant elements, and has been found to exist in many forms, including diamonds and graphene. The researchers with this new effort note that much research has been conducted into the more familiar forms (allotropes) how they are bonded. They further note that less well-known types of carbon have not received nearly as much attention. One of these, called cyclocarbon, has even been the topic of debate. Are the two-neighbor forms bonded by the same length bonds, or are there alternating bonds of shorter and longer lengths? The answer to this question has been difficult to find due to the high reactivity of such forms. The researchers with this new effort set themselves the task of finding the answer once and for all.

The team's approach involved creating a precursor molecule and then whittling it down to the desired form. To that end, they used atomic force microscopy to create linear lines of carbon atoms atop a copper substrate that was covered with salt to prevent the carbon atoms from bonding with the subsurface. They then joined the lines of atoms to form the carbon oxide precursor C24O6, a triangle-shaped form. Next, the team applied high voltage through the AFM to shear off one of the corners of the triangle, resulting in a C22O4 form. They then did the same with the other two corners. The result was a C18 ring—an 18-atom cyclocarbon. After creating the ring, the researchers found that the bonds holding it together were the alternating long- and short-type bonds that had been previously suggested.

 

Ring-shaped multi-carbon compound cyclocarbon synthesized, Bob Yirka , Phys.org

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Smart Packaging...

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Cheaper flexible integrated circuits open up new markets. (Courtesy: PragmatIC)

 

Topics: Applied Physics, Moore's Law, Semiconductor Technology, Nanotechnology


For more than 50 years, progress in the electronics industry has been guided by Moore’s law: the idea that the number of transistors in a silicon-based integrated circuit (IC) will double approximately every 18 months. The consequences of this doubling include a continual reduction in the size of silicon ICs, as it becomes possible to provide increasingly complex and high-performance functionality in smaller and smaller areas of silicon, and at progressively lower cost relative to the circuits’ processing power.

Moore’s law is an empirical rule of thumb rather than a robust physical principle, and much has been written about how, why and when it will eventually fail. But even before we reach that point, manufacturers are already finding that, in practice, the cost savings associated with reducing the size, or “footprint”, of ICs will only carry them so far. The reason is that below a certain minimum size, ICs become difficult to handle easily or effectively. For highly complex circuitry, such as that found in computers with many millions of transistors in a single IC, this limit on handling size may not be a consideration. However, for applications that require less complex circuits, the size constraint imposed by the physical aspect of handling ICs becomes a limiting factor in their cost.

The approach we have taken at PragmatIC is to use thin, flexible substrates, rather than rigid silicon, as the base for building our circuits. The low cost of the materials involved and the relatively low complexity of our target applications alters the economics around circuit footprint and overall IC cost. Accepting a larger footprint can lower capital expenditure because it means that ultrahigh-end precision tooling is not required to fabricate our circuits during the manufacturing process. In turn, for low-complexity applications, this can lead to a lower final IC cost.

The resulting flexible integrated circuits, or FlexICs, are thinner than a human hair, so they can easily be embedded in everyday objects. They also cost around 10 times less than silicon ICs, making it economically viable for them to appear in trillions of smart objects that engage with consumers and their environments. Since the technology was developed, PragmatIC FlexICs have been trialed in a wide variety of markets, including consumer goods, games, retail, and the pharmaceutical and security sectors.

 

A smart approach to smart packaging
Catherine Ramsdale is vice-president of device development at PragmatIC

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LMADIS...

Topics: Applied Physics, Electromagnetic Radiation, Politics, Robotics


I normally cheer the usage and applications of recent technology. In light of recent events, this may not be a swift idea. The second through fourth letters of the acronym are quite (and maybe intentionally) ominous.

"War is the continuation of politics by other means." Carl von Clausewitz

 

*****


In June, Iran’s military shot down one of the U.S. Navy’s $130 million Global Hawk drones, claiming it had veered out of international airspace and into the nation’s territory.

Now, the U.S. Navy has returned the favor, using a new directed-energy weapon to disable an Iranian drone in the same region — marking the next-generation device’s first known “kill.”

According to a Department of Defense statement, a fixed wing drone approached the USS Boxer while the ship traveled through the Strait of Hormuz on July 18. The drone then came within a threatening range, prompting the crew to take “defensive action.”

A defense official later told Military.com on the condition of anonymity that the Navy took out the drone using its Light Marine Air Defense Integrated System (LMADIS), a new device that uses radio frequencies to jam drones.

Iran’s Minister of Foreign Affairs Mohammad Javad Zarif, meanwhile, has denied the incident altogether, telling reporters the nation has “no information about losing a drone.”

 

US Navy's Weapon Gets First "Kill," Shoots Down Iranian Drone
Kristin Houser, Futurism

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Your iPhone as Tricorder...

Silicon chips similar to those that would be used in the detection process. Credit: Vanderbilt University/Heidi Hall

 

Topics: Applied Physics, Medical Physics, Nanotechnology, Star Trek


The simplest home medical tests might look like a deck of various silicon chips coated in special film, one that could detect drugs in the blood, another for proteins in the urine indicating infection, another for bacteria in water and the like. Add the bodily fluid you want to test, take a picture with your smart phone, and a special app lets you know if there's a problem or not.

That's what electrical engineer Sharon Weiss, Cornelius Vanderbilt Professor of Engineering at Vanderbilt University, and her students developed in her lab, combining their research on low-cost, nanostructured thin films with a device most American adults already own. "The novelty lies in the simplicity of the basic idea, and the only costly component is the smart phone," Weiss said.

"Most people are familiar with silicon as being the material inside your computer, but it has endless uses," she said. "With our nanoscale porous silicon, we've created these nanoscale holes that are a thousand times smaller than your hair. Those selectively capture molecules when pre-treated with the appropriate surface coating, darkening the silicon, which the app detects."
 

 

iPhone plus nanoscale porous silicon equals cheap, simple home diagnostics
Heidi Hall, Vanderbilt University, Phys.org

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SLIPS...

A novel, highly sensitive molecular sensor together with a first-of-its-kind histamine detector comprise abbieSense, a device that can diagnose and assess the severity of an allergic reaction within five minutes. Credit: Wyss Institute at Harvard University

 

Topics: Applied Physics, Fluid Mechanics, Microfluidics, Nanofluidics, Nanotechnology

 


The need for an inexpensive, super-repellent surface cuts across a vast swath of societal sectors—from refrigeration and architecture, to medical devices and consumer products. Most state-of-the-art liquid repellent surfaces designed in the last decade are modeled after lotus leaves, which are extremely hydrophobic due to their rough, waxy surface and the physics of their natural design. However, none of the lotus-inspired materials designed so far has met the mark: they may repel water but they fail to repel oils, fail under physical stress, cannot self-heal – and are expensive to boot.

‘SLIPS’ technology, inspired by the slippery pitcher plant that repels almost every type of liquid and solid, is a unique approach to coating industrial and medical surfaces that is based on nano/microstructured porous material infused with a lubricating fluid. By locking in water and other fluids, SLIPS technology creates slick, exceptionally repellent and robust self-cleaning surfaces on metals, plastics, optics, textiles and ceramics. These slippery surfaces repel almost any fouling challenge a surface may face—whether from bacteria, ice, water, oil, dust, barnacles, or other contaminants.

 

Wyss Institute, Harvard: Slippery Liquid Infused Porous Surfaces

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Superconductors' never-ending flow of electrical current could provide new options for energy storage and superefficient electrical transmission and generation. But the signature zero electrical resistance of superconductors is reached only below a certain critical temperature and is very expensive to achieve. Physicists in Serbia believe they've found a way to manipulate superthin, waferlike monolayers of superconductors, thus changing the material's properties to create new artificial materials for future devices. This image shows a liquid phase graphene film deposited on PET substrate. Credit: Graphene Laboratory, University of Belgrade

 

Topics: Applied Physics, Superconductors, Thin Films


Superconductors' never-ending flow of electrical current could provide new options for energy storage and superefficient electrical transmission and generation, to name just a few benefits. But the signature zero electrical resistance of superconductors is reached only below a certain critical temperature, hundreds of degrees Celsius below freezing, and is very expensive to achieve.

Physicists from the University of Belgrade in Serbia believe they've found a way to manipulate superthin, waferlike monolayers of superconductors, such as graphene, a monolayer of carbon, thus changing the material's properties to create new artificial materials for future devices. The findings from the group's theoretical calculations and experimental approaches are published in the Journal of Applied Physics.

"The application of tensile biaxial strain leads to an increase of the critical temperature, implying that achieving high temperature superconductivity becomes easier under strain," said the study's first author from the University of Belgrade's LEX Laboratory, Vladan Celebonovic.

 

Strain enables new applications of 2-D materials, Phys.org

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Good Vibes...

Sounding off: theoretical force patterns for an underwater Chladni plate at two different frequencies. The force arrows illustrate why glass beads accumulate at the plate antinodes (shown in yellow and red). (Courtesy: K Latifi, H Wijaya and Q Zhou/Physical Review Letters)

 

Topics: Acoustic Physics, Applied Physics, Research


The behaviour of some particles on the vibrating surfaces of Chladni plates is reversed underwater, a new study reveals. The discovery was made by Kourosh Latifi, Harri Wijaya, and Quan Zhou at Aalto University in Finland. They observed that glass beads on a submerged vibrating plate move towards antinodes, where the plate’s amplitude of vibration is highest. The underwater effect could be useful in a variety of medical and biological applications, including the manipulation of living cells.

In 1787 the German physicist Ernst Chladni put sand on a vibrating plate and observed that the grains settle on the nodal lines where the plate’s amplitude of vibration is zero. In contrast, he observed that finer particles move towards the plate’s antinodes where the amplitude is a local maximum.

A century later, Michael Faraday explained both behaviours. He concluded that the vibrations cause the larger grains to move laterally across the plate until they reach a node – where they no longer get lateral kicks and therefore remain in place. As for why the smaller particles did the opposite, Faraday argued that air currents just above the plates tend to push the lighter particles towards the antinodes – an effect known as acoustic streaming.

 

Vibrations guide tiny glass beads through an underwater maze
Sam Jarman, Physics World

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