Intense Lasers Shine new Light on the Electron Dynamics of Liquids

An intense laser pulse (in red) hits a flow of water molecules, inducing an ultrafast dynamics of the electrons in the liquid.
Illustration Credit: ©J. Harms, MPSD

The behavior of electrons in liquids plays a big role in many chemical processes that are important for living things and the world in general. For example, slow electrons in liquid have the capacity to cause disruptions in the DNA strand.

But electron movements are extremely hard to capture because they take place within attoseconds: the realm of quintillionths of a second. Since advanced lasers now operate at these timescales, they can offer scientists glimpses of these ultrafast processes via a range of techniques.

An international team of researchers has now demonstrated that it is possible to probe electron dynamics in liquids using intense laser fields and to retrieve the electron's mean free path - the average distance an electron can travel before colliding with another particle.

"We found that the mechanism by which liquids emit a particular light spectrum, known as the high-harmonic spectrum, is markedly different from the ones in other phases of matter like gases and solids," said Zhong Yin from Tohoku University's International Center for Synchrotron Radiation Innovation Smart (SRIS) and co-first author of the paper. "Our findings open the door to a deeper understanding of ultrafast dynamics in liquids."

Good news for the world’s rarest marine dolphin?

Māui dolphins.
Photo Credit: University of Auckland/Department of Conservation

The tiny population – only about 54 Māui dolphins remain – lives off the west coast of the North Island.

Once seen from Cook Strait to north of Kaipara, the dolphins’ range is now considerably smaller, with most sightings between Muriwai and Raglan.

The creatures' median age dropped by about a year over the course of a decade, according to research from the University of Auckland – Waipapa Taumata Rau, Oregon State University and University of California Los Angeles.

It could be good news: a population with younger dolphins will produce more calves than an older population, ultimately increasing the population size, which is vital for the dolphins' future.

“The population may be getting younger because individuals born after 2008, the year a marine sanctuary was introduced off the west coast of the North Island, have better chances of survival, since they are less likely to be accidentally caught in fishing nets,” suggests Professor Rochelle Constantine.

However, it’s also possible that older dolphins aren’t living to expected maximum ages of about 20 years.

Soil bacteria prevail despite drought conditions

ClimGrass, the field experiment in Styria, in which drought is simulated in combination with future climate conditions.
Photo Credit: Markus Herndl, HBLFA Raumberg-Gumpenstein

Recent research uncovers the resilience of certain soil microorganisms in the face of increasing drought conditions. While many bacteria become inactive during dry spells, specific groups persist and even thrive. This study, conducted by the Centre for Microbiology and Environmental Systems Science (CeMESS) at the University of Vienna, offers ground-breaking insights into bacterial activity during drought periods, with implications for agriculture and our understanding of climate change impacts. The study has been published in the renowned scientific journal Nature Communications.

The images of the parched Po Valley in 2022 and this year's forest fires in Greece underscore the reality of extreme droughts – not just as news headlines but as immediate threats. The repercussions for humans and plant life are evident: crop failures, withered meadows, and water rationing. However, the impact of drought on soil microorganisms remains hidden from the naked eye.

Soil microorganisms play a pivotal role in ecosystems. They contribute to soil fertility, assist plants in nutrient absorption, and determine whether soils store or release CO2, thereby influencing climate change trajectories. Until now, measuring the activity of microorganisms in dry soils and identifying which species remain active was challenging. Thanks to a novel method developed by scientists at the University of Vienna, bacterial activity during drought periods can now be observed.

Giant molecular rotors operate in solid crystal

Artistic depiction of a giant rotor molecule rotating in the solid state.
Illustration Credit: Rempei Ando, et al. Angewandte Chemie International Edition.

Concave, umbrella-like metal complexes provide space to enable the largest molecular rotor operational in the solid-state.

Solid materials are generally known to be rigid and unmoving, but scientists are turning this idea on its head by exploring ways to incorporate moving parts into solids. This can enable the development of exotic new materials such as amphidynamic crystals—crystals which contain both rigid and mobile components—whose properties can be altered by controlling molecular rotation within the material. 

A major challenge to achieving motion in crystals—and in solids in general—is the tightly packed nature of their structure. This restricts dynamic motion to molecules of a limited size. However, a team led by Associate Professor Mingoo Jin from the Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University has set a size record for such dynamic motion, demonstrating the largest molecular rotor shown to be operational in the solid-state.

A molecular rotor consists of a central rotating molecule that is connected by axis molecules to stationary stator molecules, similar to the way that a wheel and axle are connected to a car frame. Such systems have been previously reported, but the crystalline material in this study features an operational rotor consisting of the molecule pentiptycene, which is nearly 40% larger in diameter than previous rotors in the solid-state, marking a significant advancement. 

Biochemistry innovation to aid reef restoration, management

Close-up of coral shows individual polyps.
Photo Credit: Ty Roach

Using an innovative new approach to sampling corals, researchers at the University of Hawaiʻi at Mānoa are now able to create maps of coral biochemistry that reveal with unprecedented detail the distribution of compounds that are integral to the healthy functioning of reefs. The study was published in Communications Biology.

“This work is a major step in understanding the coral holobiont [the coral animal and all of its associated microorganisms], which is critical for reef restoration and management,” said lead author Ty Roach, who conducted this study as a postdoctoral researcher at the Hawaiʻi Institute of Marine Biology (HIMB) in the UH Mānoa School of Ocean and Earth Science and Technology.

Despite occupying a tiny fraction of the ocean, coral reefs are one of the most diverse and productive ecosystems on the planet and provide critical habitats for many species and protection for coastal communities.

Biochemicals, such as amino acids, compounds that affect development and growth, and others that have antibacterial or antioxidant properties, have a direct relation to how resilient coral will be in the face of stressors, such as warmer ocean temperatures and ocean acidification.

Why Are Killer Whales Harassing and Killing Porpoises Without Eating Them

A killer whale in the Salish Sea is observed harassing a porpoise, a behavior that has long perplexed scientists. A study from Wild Orca and UC Davis’ SeaDoc Society investigates what may be behind it.
 Photo Credit: Courtesy Wild Orca

For decades, fish-eating killer whales in the Pacific Northwest have been observed harassing and even killing porpoises without consuming them — a perplexing behavior that has long intrigued scientists.

A study published today in Marine Mammal Science, co-led by Deborah Giles of Wild Orca and Sarah Teman of the SeaDoc Society, a program of the UC Davis School of Veterinary Medicine, looked at more than 60 years of recorded interactions between Southern Resident killer whales and porpoises in the Salish Sea to better understand why they exhibit this behavior.

Southern Resident killer whales are an endangered population, numbering only 75 individuals. Their survival is intimately tied to the fortunes of chinook salmon — also an endangered species. Without enough chinook salmon, these whales are in danger of extinction.

“I am frequently asked, why don’t the Southern Residents just eat seals or porpoises instead?” said Giles. “It's because fish-eating killer whales have a completely different ecology and culture from orcas that eat marine mammals — even though the two populations live in the same waters. So we must conclude that their interactions with porpoises serve a different purpose, but this purpose has only been speculation until now.”

Researchers uncover critical clues about the origin of heart arrhythmias

Immunofluorescent staining demonstrating fibroblasts expressing the Channelrhodopsin protein in heart scar tissue. The ChR2-expressing fibroblast (green, arrow) is in close proximity to cardiomyocytes (red) within scar.
Image Credit: Courtesy of UCLA Health

In a research article published today in the journal Science, UCLA researchers have found that fibroblasts – scar-forming cells that reside in the scar tissue of an injured heart -- directly play a role in promoting a disturbance of the heart rhythm, otherwise known as an arrhythmia. This finding holds promise for novel approaches to life threatening rhythm problems of the heart. 

Every year in the U.S., sudden cardiac death kills upwards of 350,000 people who have had no previous symptoms of heart disease, and in the majority of cases, the underlying cause is an arrhythmia. While there is a strong association between the amount of scar tissue in the heart and the likelihood of an arrhythmia to occur, whether fibroblasts in scar tissue directly communicated with cardiac muscle cells to promote arrhythmias was not known.

In cardiac scar tissue, cardiac muscle cells are surrounded by cardiac fibroblasts and often come in close contact with cardiac fibroblasts. "For decades, scientists have wondered whether the cardiac fibroblasts are electrically passive and just form scar tissue or whether by coming in close contact with myocytes, they directly increased the excitability of cardiac muscle cells and promoted life threatening arrhythmias in vivo," said Dr. Arjun Deb, senior author, professor of medicine and director of the UCLA Cardiovascular Theme, at the David Geffen School of Medicine. 

Ultrasound may rid groundwater of toxic ‘forever chemicals’

PFAS is notoriously difficult to clean from the environment, but ultrasound may offer a more effective solution compared to past efforts.
Photo Credit: Edward Jenner

New research suggests that ultrasound may have potential in treating a group of harmful chemicals known as PFAS to eliminate them from contaminated groundwater.

Invented nearly a century ago, per- and poly-fluoroalkyl substances, also known as “forever chemicals,” were once widely used to create products such as cookware, waterproof clothing and personal care items. Today, scientists understand that exposure to PFAS can cause a number of human health issues such as birth defects and cancer. But because the bonds inside these chemicals don’t break down easily, they’re notoriously difficult to remove from the environment.

Such difficulties have led researchers at The Ohio State University to study how ultrasonic degradation, a process that uses sound to degrade substances by cleaving apart the molecules that make them up, might work against different types and concentrations of these chemicals.

By conducting experiments on lab-made mixtures containing three differently sized compounds of fluorotelomer sulfonates – PFAS compounds typically found in firefighting foams – their results showed that over a period of three hours, the smaller compounds degraded much faster than the larger ones. This is in contrast to many other PFAS treatment methods in which smaller PFAS are actually more challenging to treat.

Revolutionary X-ray microscope unveils sound waves deep within crystals

Scientists developed a groundbreaking technology that allows them to see sound waves and microscopic defects inside crystals, promising insights that connect ultrafast atomic motion to large-scale macroscopic behaviors.
Photo Credit: Olivier Bonin/SLAC National Accelerator Laboratory

Scientists developed a groundbreaking technology that allows them to see sound waves and microscopic defects inside crystals, promising insights that connect ultrafast atomic motion to large-scale macroscopic behaviors.

Researchers at the Department of Energy’s SLAC National Accelerator Laboratory. Stanford University, and Denmark Technical University have designed a cutting-edge X-ray microscope capable of directly observing sound waves at the tiniest of scales – the lattice level within a crystal. These findings, published last week in Proceedings of the National Academy of Sciences, could change the way scientists study ultrafast changes in materials and the resulting properties.

“The atomic structure of crystalline materials gives rise to their properties and associated ‘use-case’ for an application,” said one of the researchers, Leora Dresselhaus-Marais, an assistant professor at Stanford and SLAC. “The crystalline defects and atomic scale displacements describe why some materials strengthen while others shatter in response to the same force. Blacksmiths and semiconductor manufacturing have perfected our ability to control some types of defects, however, few techniques today can image these dynamics in real-time at the appropriate scales to resolve how those the distortions connect to the bulk properties.”

Solar cell material can assist self-driving cars in the dark

Rui Zhang, postdoc fellow at IFM is one of the principle authors to the article published in Nature Photonics.
Photo Credit: Olov Planthaber

Material used in organic solar cells can also be used as light sensors in electronics. This is shown by researchers at Linköping University who have developed a type of sensor able to detect circularly polarized red light. Their study, published in Nature Photonics, paves the way for more reliable self-driving vehicles and other uses where night vision is important.

Some beetles with shiny wings, firefly larvae and colorful mantis shrimps reflect a particular kind of light known as circularly polarized light. This is due to microscopic structures in their shell that reflect the electromagnetic light waves in a particular way.

Circularly polarized light also has many technical uses, such as satellite communication, bioimaging and other sensing technologies. This is because circularly polarizing light carries a vast amount of information, due to the fact that the electromagnetic field around the light beam spirals either to the right or to the left.