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Category: physics – Page 175

Josh SeehermanI don’t think he’s wrong.

Art ToegemannIt’s adjusting to users sharing a password.

Shubham Ghosh Roy shared a link.

At the interface between chemistry and physics, the process of crystallization is omnipresent in nature and industry. It is the basis for the formation of snowflakes but also of certain active ingredients used in pharmacology. For the phenomenon to occur for a given substance, it must first go through a stage called nucleation, during which the molecules organize themselves and create the optimal conditions for the formation of crystals. While it has been difficult to observe pre-nucleation dynamics, this key process has now been revealed by the work of a research team from the University of Geneva (UNIGE). The scientists have succeeded in visualizing this process spectroscopically in real time and on a micrometric scale, paving the way to the design of safer and more stable active substances. These results can be found in the Proceedings of the National Academy of Sciences (PNAS).

Crystallization is a chemical and physical process used in many fields, from the pharmaceutical industry to food processing. It is used to isolate a gaseous or liquid substance in the form of crystals. However, this phenomenon is not unique to industry; it is ubiquitous in nature and can be seen, for example, in snowflakes, coral or kidney stones.

For crystals to form from substances, they must first go through a crucial stage called nucleation. It is during this first phase that the molecules begin to arrange themselves to form “nuclei,” stable clusters of molecules, which leads to the development and growth of . This process occurs stochastically, meaning it is not predictable when and where a nucleus form. “Until now, scientists have been struggling to visualize this first stage at the molecular level. The microscopic picture of crystal nucleation has been under intense debate. Recent studies suggest that molecules seem to form some disordered organization before the formation of nuclei. Then how does the crystalline order emerge from them? That is a big question,” explains Takuji Adachi, assistant professor in the Department of Physical Chemistry at the UNIGE Faculty of Science.

Continue reading “Revolutionary images of the birth of crystals” | >

A new spin on one of the 20th century’s smallest but grandest inventions, the transistor, could help feed the world’s ever-growing appetite for digital memory while slicing up to 5% of the energy from its power-hungry diet.

Following years of innovations from the University of Nebraska–Lincoln’s Christian Binek and University at Buffalos Jonathan Bird and Keke He, the physicists recently teamed up to craft the first magneto-electric transistor.

Along with curbing the energy consumption of any microelectronics that incorporate it, the team’s design could reduce the number of transistors needed to store certain data by as much as 75%, said Nebraska physicist Peter Dowben, leading to smaller devices. It could also lend those microelectronics steel-trap memory that remembers exactly where its users leave off, even after being shut down or abruptly losing power.

Read more | >

A new spin on one of the 20th century’s smallest but grandest inventions, the transistor, could help feed the world’s ever-growing appetite for digital memory while slicing up to 5% of the energy from its power-hungry diet.

Following years of innovations from the University of Nebraska–Lincoln’s Christian Binek and University at Buffalo’s Jonathan Bird and Keke He, the physicists recently teamed up to craft the first magneto-electric transistor.

Along with curbing the energy consumption of any microelectronics that incorporate it, the team’s design could reduce the number of transistors needed to store certain data by as much as 75%, said Nebraska physicist Peter Dowben, leading to smaller devices. It could also lend those microelectronics steel-trap memory that remembers exactly where its users leave off, even after being shut down or abruptly losing power.

Read more | >

A new PV module makes electricity from thermal radiation. Imagine that.

The electromagnetic spectrum is comprised of thousands upon thousands of frequencies. Sound and light are all part of the spectrum, as are the frequencies that make radio and television broadcasts possible. Today’s solar panels harvest light waves from a small part of the EM spectrum and turn them into electricity, but there are many other frequencies like thermal radiation that could someday stimulate new kinds of photovoltaic cells to generate electricity as well.

Researchers at Stanford have recently published a study in the journal Applied Physics Letters that describes a new type of cell that converts thermal radiation into electricity. When the sun goes down, living organisms and physical structures like buildings, road, and sidewalks radiate heat back into the atmosphere. We call this radiational cooling and it is those electromagnetic waves the Stanford researchers say can be put to work making electricity.

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In 1,832, Charles Darwin witnessed hundreds of ballooning spiders landing on the HMS Beagle while some 60 miles offshore. Ballooning is a phenomenon that’s been known since at least the days of Aristotle—and immortalized in E.B. White’s children’s classic Charlotte’s Web—but scientists have only recently made progress in gaining a better understanding of its underlying physics.

Now, physicists have developed a new mathematical model incorporating all the various forces at play as well as the effects of multiple threads, according to a recent paper published in the journal Physical Review E. Authors M. Khalid Jawed (UCLA) and Charbel Habchi (Notre Dame University-Louaize) based their new model on a computer graphics algorithm used to model fur and hair in such blockbuster films as The Hobbit and Planet of the Apes. The work could one day contribute to the design of new types of ballooning sensors for explorations of the atmosphere.

There are competing hypotheses for how ballooning spiders are able to float off into the air. For instance, one proposal posits that, as the air warms with the rising sun, the silk threads the spiders emit to spin their “parachutes” catch the rising convection currents (the updraft) that are caused by thermal gradients. A second hypothesis holds that the threads have a static electric charge that interacts with the weak vertical electric field in the atmosphere.

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An international team, co-led by researchers at The University of Manchester’s National Graphene Institute (NGI) in the UK and the Penn State College of Engineering in the US, has developed a tunable graphene-based platform that allows for fine control over the interaction between light and matter in the terahertz (THz) spectrum to reveal rare phenomena known as exceptional points. The team published their results today in Science.

The work could advance optoelectronic technologies to better generate, control and sense light and potentially communications, according to the researchers. They demonstrated a way to control THz waves, which exist at frequencies between those of microwaves and infrared waves. The feat could contribute to the development of ‘beyond-5G’ wireless technology for high-speed communication networks.

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Using a “laser pincer,” scientists can generate their own antimatter, simulations show.

An international team of physicists have come up with a way to generate antimatter in the lab, allowing them to recreate conditions that are similar to those near a neutron star.

This setup, at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) research laboratory in Germany, involves two high-intensity laser beams that can generate a jet of antimatter, as outlined in a paper published earlier this summer in the journal Communications Physics. That could make antimatter-based research far more accessible for scientists around the world.

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