Computers Math

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.”
Details of the group’s research was published in the journal Nature Physics on September 28, 2023.
Using intense laser fields to generate high-energy photons, a phenomenon known as high-harmonic generation (HHG), is a widespread technique used in many different areas of science, for instance for probing electronic motion in materials, or tracking chemical reactions in time. HHG has been studied extensively in gases and more recently in crystals, but much less is known about liquids.
The research team, which also included researchers from the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg and ETH Zurich, reported on the unique behavior of liquids when irradiated by intense lasers. Until now, almost nothing is known about these light-induced processes in liquids, which surround us everywhere and are present in every chemical reaction. In contrast, scientists have made significant strides in recent years in exploring the behavior of solids under irradiation. Therefore, the experimental team at ETH Zurich developed a unique apparatus to specifically study the interaction of liquids with intense lasers. The researchers discovered a distinctive behavior where the maximum photon energy obtained through HHG in liquids was independent of the laser’s wavelength. What, then, was the responsible factor? More

Cheaper, more efficient lithium-ion batteries could be produced by harnessing previously overlooked high pressures generated during the manufacturing process.
Scientists at the University of Birmingham have discovered that routine ball milling can cause high pressure effects on battery materials in just a matter of minutes, providing a vital additional variable in the process of synthesizing battery materials.
The research (part of the Faraday Institution funded CATMAT project), led by Dr Laura Driscoll, Dr Elizabeth Driscoll and Professor Peter Slater at the University of Birmingham is published in RSC Energy Environmental Science.
The use of ball milling has been a huge area of growth in the lithium-ion battery space to make next generation materials. The process is simple and consists of milling powder compounds with small balls that mix and make the particles smaller, creating high-capacity electrode materials and leading to better performing batteries.
Previous studies had led experts to believe that the synthesis of these materials was caused by localised heating generated in the milling process. But now researchers have found that dynamic impacts from the milling balls colliding with the battery materials create a pressure effect which plays an important role in causing the changes.
Peter Slater, Professor of Materials Chemistry and Co-Director of the Birmingham Centre for Energy Storage at the University of Birmingham, said: “This discovery was almost an accident. We ball milled lithium molybdate as a model system to explore oxygen redox in batteries, and noticed that there was a phase transformation to the high-pressure spinel polymorph, a specific crystal structure that has only previously been made under high-pressure conditions.
“Local heating alone could not explain this transformation. To test this theory, we then ball milled three other battery materials and our findings from these milling experiments reinforced our conclusion that local heating could not be the only reason for these changes.”
The researchers also found that applying heat would cause some compounds to return to their pre-milled state, signifying that an additional variable was at play in the original synthesis: pressure being key. More

Semiconductors are the heart of almost every electronic device. Without semiconductors, our computers would not be able to process and retain data; and LED (light-emitting diode) lightbulbs would lose their ability to shine.
But semiconductor manufacturing requires a lot of energy. Forming semiconductor materials from sand (silicon oxide) consumes a significant amount of heat-intensive energy, at scorching temperatures of around 2,700 degrees Fahrenheit. And the process of purifying and assembling all the raw materials that go into making a semiconductor can take weeks if not months.
A new semiconducting material called “multielement ink” could make that process significantly less heat-intensive and more sustainable. Developed by researchers from Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley, “multielement ink” is the first “high-entropy” semiconductor that can be processed at low-temperature or room temperature. The breakthrough was recently reported in the journal Nature.
“The traditional way of making semiconductor devices is energy-intensive and one of the major sources of carbon emissions,” said Peidong Yang, the senior author on the study. Yang is a faculty senior scientist in Berkeley Lab’s Materials Sciences Division and professor of chemistry and materials science and engineering at UC Berkeley. “Our new method of making semiconductors could pave the way for a more sustainable semiconductor industry.”
The advance takes advantage of two unique families of semiconducting materials: hard alloys made of high-entropy semiconductors; and a soft, flexible material made of crystalline halide perovskites.
High-entropy materials are solids made of five or more different chemical elements that self-assemble in near-equal proportions into a single system. For many years, researchers have wanted to use high-entropy materials to develop semiconducting materials that self-assemble with minimal energy inputs.
“But high-entropy semiconductors have not been studied to nearly the same extent. Our work could help to significantly fill in that gap of understanding,” said Yuxin Jiang, co-first author and graduate student researcher in the Peidong Yang group with Berkeley Lab’s Materials Sciences Division and the department of chemistry at UC Berkeley. More

The sex hormone commonly known as estrogen plays an important role in multiple aspects of women’s health and fertility. High levels of estrogen in the body are associated with breast and ovarian cancers, while low levels of estradiol can result in osteoporosis, heart disease, and even depression. (Estrogen is a class of hormones that includes estradiol as the most potent form). Estradiol is also necessary for the development of secondary sexual characteristics in women and regulates the reproductive cycle.
Because of its many functions, the hormone estradiol is often specifically monitored by physicians as part of women’s health care, but this usually requires the patient to visit a clinic to have blood drawn for analysis in a lab. Even at-home testing kits require samples of blood or urine to be mailed to a lab.
But now Caltech researchers have developed a wearable sensor that monitors estradiol by detecting its presence in sweat. The researchers say the sensor may one day make it easier for women to monitor their estradiol levels at home and in real time.
The research was conducted in the lab of Wei Gao, assistant professor of medical engineering, investigator with the Heritage Medical Research Institute, and Ronald and JoAnne Willens Scholar. In recent years, Gao has developed sweat sensors that detect cortisol, a hormone associated with stress; the presence of the COVID-19 virus; a biomarker indicating inflammation in the body; and a whole slew of other nutrients and biological compounds.
Gao says the development of the estradiol sensor was spurred in part by requests from people who were unsatisfied with the options they had for monitoring their estrogen levels and had seen his previous work.
“People often ask me if I could make the same kind of sweat sensor for female hormones, because we know how much those hormones impact women’s health,” Gao says.
One population of women who would benefit from estradiol monitoring are those who are attempting to conceive a child, either naturally or through in vitro fertilization. The success of either method is dependent on getting timing right with regards to ovulation, but not all women have a reproductive cycle that follows a regular schedule. Some women have been able to track their ovulation by monitoring their body temperature, but Gao says that method has limited usefulness because it’s not very accurate and body temperature doesn’t increase until ovulation has begun. More

Patterns of chemical interactions are thought to create patterns in nature such as stripes and spots. This new study shows that the mathematical basis of these patterns also governs how sperm tail moves.
The findings, published today in Nature Communications, reveal that flagella movement of, for example, sperm tails and cilia, follow the same template for pattern formation that was discovered by the famous mathematician Alan Turing.
Flagellar undulations make stripe patterns in space-time, generating waves that travel along the tail to drive the sperm and microbes forward.
Alan Turing is most well-known for helping to break the enigma code during WWII. However he also developed a theory of pattern formation that predicted that chemical patterns may appear spontaneously with only two ingredients: chemicals spreading out (diffusing) and reacting together. Turing first proposed the so-called reaction-diffusion theory for pattern formation.
Turing helped to pave the way for a whole new type of enquiry using reaction-diffusion mathematics to understand natural patterns. Today, these chemical patterns first envisioned by Turing are called Turing patterns. Although not yet proven by experimental evidence, these patterns are thought to govern many patterns across nature, such as leopard spots, the whorl of seeds in the head of a sunflower, and patterns of sand on the beach. Turing’s theory can be applied to various fields, from biology and robotics to astrophysics.
Mathematician Dr Hermes Gadêlha, head of the Polymaths Lab, and his PhD student James Cass conducted this research in the School of Engineering Mathematics and Technology at the University of Bristol. Gadêlha explained: “Live spontaneous motion of flagella and cilia is observed everywhere in nature, but little is known about how they are orchestrated.
“They are critical in health and disease, reproduction, evolution, and survivorship of almost every aquatic microorganism in earth.”
The team was inspired by recent observations in low viscosity fluids that the surrounding environment plays a minor role on the flagellum. They used mathematical modelling, simulations, and data fitting to show that flagellar undulations can arise spontaneously without the influence of their fluid environment. More

A groundbreaking development in biomedical engineering has led to the creation of a human stomach micro-physiological system (hsMPS), representing a significant leap forward in understanding and treating various gastrointestinal diseases, including stomach cancer. The research team, led by Professor Tae-Eun Park from the Department of Biomedical Engineering at UNIST and Professor Seong-Ho Kong from Seoul National University Hospital, has successfully developed a biomimetic chip that combines organoid and organ-on-a-chip technologies to simulate the complex defense mechanisms of the human gastric mucosa.
Organoids, which mimic human organs using stem cells, have shown great potential as in vitro models for studying specific functions. However, they lack the ability to replicate mechanical stimulation or cell-to-cell interactions found within the human body. This limitation prompted researchers to develop an innovative biochip capable of recreating real-life gastric mucosal protection systems.
The newly developed biochip incorporates fluid flow within its microfluidic channels to simulate mechanical stimuli and facilitate cell-to-cell interactions. Mesenchymal substrate cells exposed to fluid flow activate gastric stem cell proliferation while promoting cellular differentiation balance. This process ultimately mimics key features necessary for developing functional gastric mucosal barriers at a biologically relevant level.
One remarkable achievement demonstrated by this hsMPS is its ability to uncover previously unseen defense mechanisms against Helicobacter pylori — a pathogen associated with various stomach diseases — in ways that were not possible with existing models. Gastric mucosal peptide known as TFF1 was observed forming mosaic-like structures within groups infected with Helicobacter pylori — forming a protective barrier essential for establishing an efficient defense system against external infectious factors. Suppression of gastric mucosal peptide expression resulted in more severe inflammatory reactions.
“This study presents our model’s potential for observing dynamic interactions between epithelial cells and immune cells in chips infected with Helicobacter pylori, contributing to a comprehensive understanding of gastric mucosal barrier stability,” explained Professor Park.
The research findings, supported by the Basic Research Laboratory (BRL) research grant from the National Research (NRF), funded by the Ministry of Science and ICT (MSIT), have been published online on July 31 in Advanced Science.
These groundbreaking advancements in hsMPS open up new avenues for studying host-microbe interactions, developing therapeutic strategies for gastric infections, and gaining a deeper understanding of gastrointestinal diseases. This innovative biochip technology has the potential to reduce reliance on animal experimentation while providing valuable insights into complex physiological processes within the human stomach. More

Quantum mechanics is a branch of physics that explores the properties and interactions of iparticles at very small scale, such as atoms and molecules. This has led to the development of new technologies that are more powerful and efficient compared to their conventional counterparts, causing breakthroughs in areas such as computing, communication, and energy.
At the Okinawa Institute of Science and Technology (OIST), researchers at the Quantum Systems Unit have collaborated with scientists from the University of Kaiserslautern-Landau and the University of Stuttgart to design and build an engine that is based on the special rules that particles obey at very small scales.
They have developed an engine that uses the principles of quantum mechanics to create power, instead of the usual way of burning fuel. The paper describing these results is co-authored by OIST researchers Keerthy Menon, Dr. Eloisa Cuestas, Dr. Thomas Fogarty and Prof. Thomas Busch and has been published in the journal Nature.
In a classical car engine, usually a mixture of fuel and air is ignited inside a chamber. The resulting explosion heats the gas in the chamber, which in turn pushes a piston in and out, producing work that turns the wheels of the car.
In their quantum engine the scientists have replaced the use of heat with a change in the quantum nature of the particles in the gas. To understand how this change can power the engine, we need to know that all particles in nature can be classified as either bosons or fermions, based on their special quantum characteristics.
At very low temperatures, where quantum effects become important, bosons have a lower energy state than fermions, and this energy difference can be used to power an engine. Instead of heating and cooling a gas cyclically like a classical engine does, the quantum engine works by changing bosons into fermions and back again.
“To turn fermions into bosons, you can take two fermions and combine them into a molecule. This new molecule is a boson. Breaking it up allows us to retrieve the fermions again. By doing this cyclically, we can power the engine without using heat,” Prof. Thomas Busch, leader of the Quantum Systems Unit explained. More

Is it possible to make a femtosecond laser entirely out of glass? That’s the rabbit hole that Yves Bellouard, head of EPFL’s Galatea Laboratory, went down after years of spending hours — and hours — aligning femtosecond lasers for lab experiments.
The Galatea laboratory is at the crossroads between optics, mechanics and materials science, and femtosecond lasers is a crucial element of Bellouard’s work. Femtosecond lasers produce extremely short and regular bursts of laser light and have many applications such as laser eye surgery, non-linear microscopy, spectroscopy, laser material processing and recently, sustainable data storage. Commercial femtosecond lasers are made by putting optical components and their mounts on a substrate, typically optical breadboards, which requires fastidious alignment of the optics.
“We use femtosecond lasers for our research on the non-linear properties of materials and how materials can be modified in their volume,” explains Bellouard. “Going through the exercise of painful complex optical alignments makes you dream of simpler and more reliable ways to align complex optics.”
Bellouard and his team’s solution? Use a commercial femtosecond laser to make a femtosecond laser out of glass, no bigger than the size of a credit card, and with less alignment hassles. The results are published in the journal Optica.
How to make a femtosecond laser out of glass
To make a femtosecond laser using a glass substrate, the scientists start with a sheet of glass. “We want to make stable lasers, so we use glass because it has a lower thermal expansion than conventional substrates, it is a stable material and transparent for the laser light we use,” Bellouard explains.
Using a commercial femtosecond laser, the scientists etch out special grooves in the glass that allow for the precise placement of the essential components of their laser. Even at micron level precision fabrication, the grooves and the components are not sufficiently precise by themselves to reach laser quality alignment. In other words, the mirrors are not yet perfectly aligned, so at this stage, their glass device is not yet functional as a laser. More