Interesting websites ( OPEN SUBJECTS)

Discussions in the vein that would most interest those looking for the "meat and potatoes" of Townsend Brown's scientific work.

Re: Interesting websites ( OPEN SUBJECTS)

Postby ecker2011 » Sat Dec 23, 2017 5:39 pm

As I have stated here that all of this really isn’t anything new. This sort of thing has been going on for a very long time.

What we should really be doing is asking not to the fact that they are releasing this information at this time but really why are they doing it? What is the motive behind all of this? For so long the government has denied all of this and now suddenly there admitting to it. Why?

Something for all of us to really think about! Don’t you agree?
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Re: Interesting websites ( OPEN SUBJECTS)

Postby ecker2011 » Wed Jan 03, 2018 1:56 pm

Physicists take first step toward cell-sized robots
by Tom Fleischman, Cornell University

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An electricity-conducting, environment-sensing, shape-changing machine the size of a human cell? Is that even possible?

Cornell physicists Paul McEuen and Itai Cohen not only say yes, but they've actually built the "muscle" for one.

With postdoctoral researcher Marc Miskin at the helm, the team has made a robot exoskeleton that can rapidly change its shape upon sensing chemical or thermal changes in its environment. And, they claim, these microscale machines – equipped with electronic, photonic and chemical payloads – could become a powerful platform for robotics at the size scale of biological microorganisms.

"You could put the computational power of the spaceship Voyager onto an object the size of a cell," Cohen said. "Then, where do you go explore?"

"We are trying to build what you might call an 'exoskeleton' for electronics," said McEuen, the John A. Newman Professor of Physical Science and director of the Kavli Institute at Cornell for Nanoscale Science. "Right now, you can make little computer chips that do a lot of information-processing … but they don't know how to move or cause something to bend."

Their work is outlined in "Graphene-based Bimorphs for Micron-sized, Autonomous Origami Machines," published Jan. 2 in Proceedings of the National Academy of Sciences. Miskin is lead author; other contributors included David Muller, the Samuel B. Eckert Professor of Engineering, and doctoral students Kyle Dorsey, Baris Bircan and Yimo Han.

The machines move using a motor called a bimorph. A bimorph is an assembly of two materials – in this case, graphene and glass – that bends when driven by a stimulus like heat, a chemical reaction or an applied voltage. The shape change happens because, in the case of heat, two materials with different thermal responses expand by different amounts over the same temperature change.

As a consequence, the bimorph bends to relieve some of this strain, allowing one layer to stretch out longer than the other. By adding rigid flat panels that cannot be bent by bimorphs, the researchers localize bending to take place only in specific places, creating folds. With this concept, they are able to make a variety of folding structures ranging from tetrahedra (triangular pyramids) to cubes.

In the case of graphene and glass, the bimorphs also fold in response to chemical stimuli by driving large ions into the glass, causing it to expand. Typically this chemical activity only occurs on the very outer edge of glass when submerged in water or some other ionic fluid. Since their bimorph is only a few nanometers thick, the glass is basically all outer edge and very reactive.

"It's a neat trick," Miskin said, "because it's something you can do only with these nanoscale systems."

The bimorph is built using atomic layer deposition – chemically "painting" atomically thin layers of silicon dioxide onto aluminum over a cover slip – then wet-transferring a single atomic layer of graphene on top of the stack. The result is the thinnest bimorph ever made.

One of their machines was described as being "three times larger than a red blood cell and three times smaller than a large neuron" when folded. Folding scaffolds of this size have been built before, but this group's version has one clear advantage.

"Our devices are compatible with semiconductor manufacturing," Cohen said. "That's what's making this compatible with our future vision for robotics at this scale."

And due to graphene's relative strength, Miskin said, it can handle the types of loads necessary for electronics applications.

"If you want to build this electronics exoskeleton," he said, "you need it to be able to produce enough force to carry the electronics. Ours does that."

For now, these tiniest of tiny machines have no commercial application in electronics, biological sensing or anything else. But the research pushes the science of nanoscale robots forward, McEuen said.

"Right now, there are no 'muscles' for small-scale machines," he said, "so we're building the small-scale muscles."


https://phys.org/news/2018-01-physicist ... obots.html
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Re: Interesting websites ( OPEN SUBJECTS)

Postby ecker2011 » Tue Jan 16, 2018 1:32 pm

X-rays reveal chirality in swirling electric vortices
by Glenn Roberts Jr., Lawrence Berkeley National Laboratory

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Just as people can be left-handed or right-handed, scientists have observed chirality or “handedness” in swirling electric vortices in a layered material. Credit: Pixabay

Scientists used spiraling X-rays at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) to observe, for the first time, a property that gives handedness to swirling electric patterns – dubbed polar vortices – in a synthetically layered material.

This property, also known as chirality, potentially opens up a new way to store data by controlling the left- or right-handedness in the material's array in much the same way magnetic materials are manipulated to store data as ones or zeros in a computer's memory.

Researchers said the behavior also could be explored for coupling to magnetic or optical (light-based) devices, which could allow better control via electrical switching.

Chirality is present in many forms and at many scales, from the spiral-staircase design of our own DNA to the spin and drift of spiral galaxies; it can even determine whether a molecule acts as a medicine or a poison in our bodies.

A molecular compound known as d-glucose, for example, which is an essential ingredient for human life as a form of sugar, exhibits right-handedness. Its left-handed counterpart, l-glucose, though, is not useful in human biology.

"Chirality hadn't been seen before in this electric structure," said Elke Arenholz, a senior staff scientist at Berkeley Lab's Advanced Light Source (ALS), which is home to the X-rays that were key to the study, published Jan. 15 in the journal Proceedings of the National Academy of Sciences.

The experiments can distinguish between left-handed chirality and right-handed chirality in the samples' vortices. "This offers new opportunities for fundamentally new science, with the potential to open up applications," she said.

"Imagine that one could convert a right-handed form of a molecule to its left-handed form by applying an electric field, or artificially engineer a material with a particular chirality," said Ramamoorthy Ramesh, a faculty senior scientist in Berkeley Lab's Materials Sciences Division and associate laboratory director of the Lab's Energy Technologies Area, who co-led the latest study.

Ramesh, who is also a professor of materials science and physics at UC Berkeley, custom-made the novel materials at UC Berkeley.

Padraic Shafer, a research scientist at the ALS and the lead author of the study, worked with Arenholz to carry out the X-ray experiments that revealed the chirality of the material.

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his diagram shows the setup for the X-ray experiment that explored chirality, or handedness, in a layered material. The blue and red spirals at upper left show the X-ray light that was used to probe the material. The X-rays scattered off of the layers of the material (arrows at upper right and associated X-ray images at top), allowing researchers to measure chirality in swirling electrical vortices within the material. Credit: Berkeley Lab

The samples included a layer of lead titanate (PbTiO3) and a layer of strontium titanate (SrTiO3) sandwiched together in an alternating pattern to form a material known as a superlattice. The materials have also been studied for their tunable electrical properties that make them candidates for components in precise sensors and for other uses.

Neither of the two compounds show any handedness by themselves, but when they were combined into the precisely layered superlattice, they developed the swirling vortex structures that exhibited chirality.

"Chirality may have additional functionality," Shafer said, when compared to devices that use magnetic fields to rearrange the magnetic structure of the material.

The electronic patterns in the material that were studied at the ALS were first revealed using a powerful electron microscope at Berkeley Lab's National Center for Electron Microscopy, a part of the Lab's Molecular Foundry, though it took a specialized X-ray technique to identify their chirality.

"The X-ray measurements had to be performed in extreme geometries that can't be done by most experimental equipment," Shafer said, using a technique known as resonant soft X-ray diffraction that probes periodic nanometer-scale details in their electronic structure and properties.

Spiraling forms of X-rays, known as circularly polarized X-rays, allowed researchers to measure both left-handed and right-handed chirality in the samples.

Arenholz, who is also a faculty member of the UC Berkeley Department of Materials Science & Engineering, added, "It took a lot of time to understand the results, and a lot of modeling and discussions." Theorists at the University of Cantabria in Spain and their network of computational experts performed calculations of the vortex structures that aided in the interpretation of the X-ray data.

The same science team is pursuing studies of other types and combinations of materials to test the effects on chirality and other properties.

"There is a wide class of materials that could be substituted," Shafer said, "and there is the hope that the layers could be replaced with even higher functionality materials."

Researchers also plan to test whether there are new ways to control the chirality in these layered materials, such as by combining materials that have electrically switchable properties with those that exhibit magnetically switchable properties.

"Since we know so much about magnetic structures," Arenholz said, "we could think of using this well-known connection with magnetism to implement this newly discovered property into devices."

https://phys.org/news/2018-01-x-rays-re ... ctric.html
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Re: Interesting websites ( OPEN SUBJECTS)

Postby ecker2011 » Wed Jan 31, 2018 4:29 pm

Speed of light drops to zero at 'exceptional points'
by Lisa Zyga

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Artistic image. Credit: pixabay

Light, which travels at a speed of 300,000 km/sec in a vacuum, can be slowed down and even stopped completely by methods that involve trapping the light inside crystals or ultracold clouds of atoms. Now in a new study, researchers have theoretically demonstrated a new way to bring light to a standstill: they show that light stops at "exceptional points," which are points at which two light modes come together and coalesce, in waveguides that have a certain kind of symmetry.

Unlike most other methods that are used to stop light, the new method can be tuned to work with a wide range of frequencies and bandwidths, which may offer an important advantage for future slow-light applications.

The researchers, Tamar Goldzak and Nimrod Moiseyev at the Technion – Israel Institute of Technology, along with Alexei A. Mailybaev at the Instituto de Matemática Pura e Aplicada (IMPA) in Rio de Janeiro, have published a paper on stopping light at exceptional points in a recent issue of Physical Review Letters.

As the researchers explain, exceptional points can be created in waveguides in a straightforward way, by varying the gain/loss parameters so that two light modes coalesce (combine into one mode). Although light stops at these exceptional points, in most systems much of the light is lost at these points. The researchers showed that this problem can be fixed by using waveguides with parity-time (PT) symmetry, since this symmetry ensures that the gain and loss are always balanced. As a result, the light intensity remains constant when the light approaches the exceptional point, eliminating losses.

To release the stopped light and accelerate it back up to normal speed, the scientists showed that the gain/loss parameters can simply be reversed. The most important feature of the new method, however, is that the exceptional points can be adjusted to work with any frequency of light, again simply by tuning the gain/loss parameters. The researchers also expect that this method can be used for other types of waves besides light, such as acoustic waves. They plan to further investigate these possibilities in the future.

https://phys.org/news/2018-01-exceptional.html
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Re: Interesting websites ( OPEN SUBJECTS)

Postby ecker2011 » Mon Feb 12, 2018 4:49 pm

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Physics Today

Born on this day in 1804 in what is now Tartu, Estonia, Heinrich (Emil) Lenz was a physicist who specialized in electromagnetism. After completing his education, Lenz joined an expedition sailing around the world from 1823 to 1826 and then began working at the University of St. Petersburg until his death in 1865. Lenz is primarily known for formulating the law that adapts Newton's third law to electromagnetic circuits. He also independently discovered Joule's law in 1842 and assisted Moritz von Jacobi in the development of electroplating technology.
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