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Comment by Dr. Krishna Kumari Challa on February 3, 2021 at 11:37am

How do electrons close to Earth reach almost the speed of light?

A new study found that electrons can reach ultra-relativistic energies for very special conditions in the magnetosphere when space is devoid of plasma.

Recent measurements from NASA's Van Allen Probes spacecraft showed that electrons can reach ultra-relativistic energies flying at almost the speed of light.  Researchers  have revealed under which conditions such strong accelerations occur. They had already demonstrated in 2020 that during solar storm plasma waves play a crucial role for that. However, it was previously unclear why such high electron energies are not achieved in all solar storms. In the journal Science Advances, they now show that extreme depletions of the background plasma density are crucial.

At ultra-relativistic energies, electrons move at almost the speed of light. Then the laws of relativity become most important. The mass of the particles increases by a factor ten, time is slowing down, and distance decreases. With such high energies, charged particles become most dangerous to even the best protected satellites. As almost no shielding can stop them, their charge can destroy sensitive electronics. Predicting their occurrence—for example, as part of the observations of space weather practiced at the GFZ—is therefore very important for modern infrastructure.

This study shows that electrons in the Earth's radiation belt can be promptly accelerated locally to ultra-relativistic energies, if the conditions of the plasma environment—plasma waves and temporarily low plasma density—are right. The particles can be regarded as surfing on plasma waves. In regions of extremely low plasma density they can just take a lot of energy from plasma waves. Similar mechanisms may be at work in the magnetospheres of the outer planets such as Jupiter or Saturn and in other astrophysical objects.

 Hayley J. Allison et al, Gyroresonant wave-particle interactions with chorus waves during extreme depletions of plasma density in the Van Allen radiation belts, Science Advances (2021). DOI: 10.1126/sciadv.abc0380

https://phys.org/news/2021-02-electrons-earth.html?utm_source=nwlet...

Comment by Dr. Krishna Kumari Challa on February 3, 2021 at 11:30am

Why food sticks to nonstick frying pans

Despite the use of nonstick frying pans, foods will sometimes get stuck to a heated surface, even if oil is used. The results can be very messy and unappetizing.

Scientists at the Czech Academy of Sciences began an investigation of the fluid properties of oil on a flat surface, such as a frying pan. Their work, reported in Physics of Fluids, shows convection may be to blame for our stuck-on food.

The experimental investigation used a nonstick pan with a surface comprised of ceramic particles. A video camera was placed above the pan as it was heated and used to measure the speed at which a dry spot formed and grew. Further experiments with a Teflon-coated pan showed the same.

Researchers experimentally explained why food sticks to the center of the frying pan. This is caused by the formation of a dry spot in the thin sunflower oil film as a result of thermocapillary convection.

When the pan is heated from below, a temperature gradient is established in the oil film. For common liquids, such as the sunflower oil used in the experiment, the surface tension decreases when temperature increases. A surface tension gradient is established, directed away from the center where the temperature is higher and toward the pan's periphery.

This gradient sets up a type of convection known as thermocapillary convection, which moves oil outward. When the oil film in the middle becomes thinner than a critical value, the film ruptures.

The researchers determined the conditions that lead to dry spots for both stationary and flowing films. These conditions include a decrease in the local film thickness below a critical size as well as the size of the deformed region falling below a number known as the capillary length.

"To avoid unwanted dry spots, the following set of measures should be applied: increasing the oil film thickness, moderate heating, completely wetting the surface of the pan with oil, using a pan with a thick bottom, or stirring food regularly during cooking.

The phenomenon also occurs in other situations, such as the thin liquid films used in fluid distillation columns or other devices that may have electronic components.

"Dry spot formation or film rupture plays a negative role, resulting in sharp overheating of the electronic components. The results of this study may, therefore, have wider application.

"On formation of dry spots in heated liquid films" Physics of Fluids (2021). DOI: 10.1063/5.0035547

https://phys.org/news/2021-02-food-nonstick-pans.html?utm_source=nw...

Comment by Dr. Krishna Kumari Challa on February 3, 2021 at 11:25am

Researchers map non-visible materials at nanoscale with ultrasound

The increasing miniaturization of electrical components in industry requires a new imaging technique at the nanometre scale. Delft researcher Gerard Verbiest and ASML have developed a first proof-of-concept method that they now plan to further develop. The method uses the same principle as ultrasound scanning in pregnancies, but on a much, much smaller scale.

Existing non-destructive imaging techniques for nanoelectronics, such as optical and electron microscopy, are not accurate enough or applicable to deeper structures. A well-known 3-D technique on a macro-scale is ultrasound. The advantage here is that it works for every sample. That makes ultrasound an excellent way of mapping the 3-D structure of a non-transparent sample in a non-destructive way." And yet, ultrasound technology at the nanoscale didn't exist yet. Indeed, the resolution of ultrasound imaging is strongly determined by the wavelength of the sound used, and that is typically around a millimeter.

o improve this, ultrasound has already been integrated into an Atomic Force Microscope (AFM).

AFM is a technique that allows you to scan and map out surfaces extremely accurately with a tiny needle. The advantage here is that it isn't the wavelength but the size of the tip of the AFM that determines the resolution. Unfortunately, at the frequencies used so far (1-10 MHz), the response of the AFM is small and unclear. We do see something, but it's not clear exactly what we're seeing. So the frequency of the sound used needed to be further increased, to the GHz range, and that's what these researchers have now done.

They have achieved this  through photoacoustics. Using the photoacoustic effect allows you to generate extremely short sound pulses. Researchers have managed to integrate this technique into an AFM. With the tip of the AFM, they c ould focus the signal. 

But there are certainly potential applications outside of electronics as well. You could use it in cell biology to make a detailed 3-D image of a single living cell, for example of the way mitochondria are folded in a cell. And in materials science, you could use it for research into heat transport in an amazing material such as graphene."

https://phys.org/news/2021-02-non-visible-materials-nanoscale-ultra...

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Comment by Dr. Krishna Kumari Challa on February 3, 2021 at 11:19am

Twisted van der Waals materials as a new platform to realize exotic...

Researchers from the MPSD, the RWTH Aachen University and the Flatiron Institute, Columbia University (both in the U.S.) and part of the Max Planck—New York City Center for Non-equilibrium Quantum Phenomena have provided a fresh perspective on the potential of twisted van der Waals materials for realizing novel and elusive states of matter and providing a unique materials-based quantum simulation platform.

Comment by Dr. Krishna Kumari Challa on February 3, 2021 at 8:54am

Say goodbye to the dots and dashes to enhance optical storage media

Innovators have created technology aimed at replacing Morse code with colored "digital characters" to modernize optical storage. They are confident the advancement will help with the explosion of remote data storage during and after the COVID-19 pandemic.

Morse code has been around since the 1830s. The familiar dots and dashes system may seem antiquated given the amount of information needed to be acquired, digitally archived and rapidly accessed every day. But those same basic dots and dashes are still used in many optical media to aid in storage.

A new technology developed at Purdue is aimed at modernizing the optical digital storage technology. Rather than using the traditional dots and dashes as commonly used in these technologies, the  innovators encode information in the angular position of tiny antennas, allowing them to store more data per unit area.

The storage capacity greatly increases because it is only defined by the resolution of the sensor by which you can determine the angular positions of antennas. They mapped the antenna angles into colors, and the colors are decoded.

This advancement allows for more data to be stored and for that data to be read at a quicker rate. The research is published in Laser & Photonics Reviews.

 Maowen Song et al, Enabling Optical Steganography, Data Storage, and Encryption with Plasmonic Colors, Laser & Photonics Reviews (2021). DOI: 10.1002/lpor.202000343

https://phys.org/news/2021-02-goodbye-dots-dashes-optical-storage.h...

Comment by Dr. Krishna Kumari Challa on February 3, 2021 at 8:41am

A new way to make wood transparent, stronger and lighter than glass

A team of researchers at the University of Maryland, has found a new way to make wood transparent. In their paper published in the journal Science Advances, the group describes their process and why they believe it is better than the old process.

Qinqin Xia et al. Solar-assisted fabrication of large-scale, patternable transparent wood, Science Advances (2021). DOI: 10.1126/sciadv.abd7342

https://phys.org/news/2021-02-wood-transparent-stronger-lighter-gla...

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Comment by Dr. Krishna Kumari Challa on February 3, 2021 at 8:38am

An origami-inspired medical patch for sealing internal injuries

Many surgeries today are performed via minimally invasive procedures, in which a small incision is made and miniature cameras and surgical tools are threaded through the body to remove tumors and repair damaged tissues and organs. The process results in less pain and shorter recovery times compared to open surgery.

While many procedures can be performed in this way, surgeons can face challenges at an important step in the process: the sealing of internal wounds and tears.

The bioadhesives currently used in minimally invasive surgeries are available mostly as biodegradable liquids and glues that can be spread over damaged tissues. When these glues solidify, however, they can stiffen over the softer underlying surface, creating an imperfect seal. Blood and other biological fluids can also contaminate glues, preventing successful adhesion to the injured site. Glues can also wash away before an injury has fully healed, and, after application, they can also cause inflammation and scar tissue formation.

Taking inspiration from origami, MIT engineers have now designed a medical patch that can be folded around minimally invasive surgical tools and delivered through airways, intestines, and other narrow spaces, to patch up internal injuries. The patch resembles a foldable, paper-like film when dry. Once it makes contact with wet tissues or organs, it transforms into a stretchy gel, similar to a contact lens, and can stick to an injured site.

Given the limitations of current designs, the team aimed to engineer an alternative that would meet three functional requirements. It should be able to stick to the wet surface of an injured site, avoid binding to anything before reaching its destination, and once applied to an injured site resist bacterial contamination and excessive inflammation.

The team's design meets all three requirements, in the form of a three-layered patch. The middle layer is the main bioadhesive, made from a hydrogel material that is embedded with compounds called NHS esters. When in contact with a wet surface, the adhesive absorbs any surrounding water and becomes pliable and stretchy, molding to a tissue's contours. Simultaneously, the esters in the adhesive form strong covalent bonds with compounds on the tissue surface, creating a tight seal between the two materials. 

This could be used to repair a perforation from a coloscopy, or seal solid organs or blood vessels after a trauma or elective surgical intervention. Instead of having to carry out a full open surgical approach, one could go from the inside to deliver a patch to seal a wound at least temporarily and maybe even long-term.

In contrast to existing surgical adhesives, the team's new tape is designed to resist contamination when exposed to bacteria and bodily fluids. Over time, the patch can safely biodegrade away. The team has published its results in the journal Advanced Materials.

Sarah J. Wu et al. A Multifunctional Origami Patch for Minimally Invasive Tissue Sealing, Advanced Materials (2021). DOI: 10.1002/adma.202007667

https://phys.org/news/2021-02-origami-inspired-medical-patch-intern...

Comment by Dr. Krishna Kumari Challa on February 2, 2021 at 11:59am

A new treatment to help people with a spinal cord injury

Comment by Dr. Krishna Kumari Challa on February 2, 2021 at 11:59am

A call for a global ban on lead paint

Once lead paint is on a wall, it becomes an expensive problem to fix. In impoverished settings, be they neighborhoods in Philadelphia or developing nations globally, remediation can be prohibitively costly.

Branches and treetops can reduce greenhouse gas emission from heavy...

New research from University of Gävle shows that forest residues can generate large amounts of biofuel, and, in the long run, reduce greenhouse gas emission by 88-94% from heavy transport on Swedish roads.

Water disinfection with ozone

While chlorine and ultraviolet light are the standard means of disinfecting water, ozone is equally effective in killing germs. To date, ozone has only been used as an oxidation agent for treating water in large plants. Now, however, a project consortium from Schleswig-Holstein is developing a miniaturized ozone generator for use in smaller applications such as water dispensers or small domestic appliances. The Fraunhofer Institute for Silicon Technology ISIT has provided the sensor chip and electrode substrates for the electrolysis cell.

Comment by Dr. Krishna Kumari Challa on February 2, 2021 at 10:40am

Virtual conference CO2 emissions quantified in new study

The virtual conferencing that has replaced large, in-person gatherings in the age of COVID-19 represents a drastic reduction in carbon emissions, but those online meetings still come with their own environmental costs, new research from the University of Michigan shows.

The research offers a framework for analyzing and tallying the carbon emissions of an online conference based on factors that include everything from energy used by servers and monitors to the resources used to manufacture and distribute the computers involved.

Individuals could skip features like gallery view, disable HD video and repair instead of replace computers to extend their useful lifetimes.

Grant Faber. A framework to estimate emissions from virtual conferences, International Journal of Environmental Studies (2021). DOI: 10.1080/00207233.2020.1864190

https://phys.org/news/2021-02-virtual-conference-co2-emissions-quan...

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