The team created a transparent, biocompatible ultrasound transducer chip that resembles a microscope glass slide and can be inserted into any optical microscope for easy viewing. Cells can be cultured and stimulated directly on top of the transducer chip and the cells’ resulting changes can be imaged with optical microscopy techniques.

Published in the Royal Society of Chemistry’s journal Lab on a Chip, the paper was selected as the cover article for the December 2021 issue. Future applications of the technology could impact stem cell, cancer and neuroscience research.

“In the conventional ultrasound stimulation experiments, a cell culture dish is placed in a water bath, and a bulky ultrasound transducer directs the ultrasound waves to the cells through the water medium,” said Sri-Rajasekhar “Raj” Kothapalli, principal investigator and assistant professor of biomedical engineering at Penn State. “This was a complex setup that didn’t provide reproducible results: The results that one group saw another did not, even while using the same parameters, because there are several things that could affect the cells’ survival and stimulation while they are in water, as well as how we visualize them.”

Kothapalli and his collaborators miniaturized the ultrasound stimulation setup by creating a transparent transducer platform made of a piezoelectric lithium niobate material. Piezoelectric materials generate mechanical energy when electric voltage is applied. The chip’s biocompatible surface allows the cells to be cultured directly on the transducer and used for repeated stimulation experiments over several weeks.

When connected to a power supply, the transducer emits ultrasound waves, which pulse the cells and trigger ion influx and outflux.

To test the setup, Kothapalli and his team cultured bladder cancer cells on the chip. They then inserted fluorescent calcium indicators into the cells to allow researchers to clearly see dynamic changes in cell calcium signaling under the microscope during stimulation.

“Since the cells are directly sitting on the transparent transducer surface, we can confirm that all the cells are equally stimulated at the same time using a single ultrasound stimulus, unlike conventional approaches,” Kothapalli, a co-hire with the Penn State Cancer Institute, said. “And unlike earlier processes, we can get high resolution images of many cells at once in a single field of view, because we are able to see the cells from a close distance.”

Through the bladder cancer cell study, researchers established proof-of-concept for the new transducer setup. But they can extend these findings to use the transducer setup in potential future applications, according to Kothapalli, such as stem cell differentiation, mechanosensitive neuromodulation, drug delivery and the opening of the blood-brain barrier.

“This simple setup will be invaluable for researchers interested in modulating cells and tissues with an ultrasound,” said Pak Kin Wong, professor of biomedical engineering, mechanical engineering and surgery at Penn State and co-author on the paper. “It can be used to explore novel therapeutic ultrasound applications, such as focused ultrasound immunotherapy.”

The ultrasound stimulation chip is low-cost, easy to fabricate, compact and scalable in size, and disposable and reusable, according to Haoyang Chen, first author of the paper and doctoral student under Kothapalli in biomedical engineering.

“It is easy to grow cells on the chip using standard cell culturing methods,” Chen said. “The setup provides controllable stimulation parameters for a variety of experiments and can be imaged with all conventional optical microscopy techniques.”

In addition to Kothapalli, Wong and Chen, other contributors to the study were Peter Butler, Penn State professor of biomedical engineering and associate dean for education and graduate professional programs; biomedical engineering graduate students Ninghao Zhu, Mohamed Osman and Shubham Khandare; and biomedical engineering undergraduate students Ryan Biskowitz and Jinyun Liu.

The study was partially funded by the Penn State Cancer Institute, a Penn State multidisciplinary seed grant, and the National Science Foundation.

Story Source:

Materials provided by Penn State. Original written by Mariah Chuprinski. Note: Content may be edited for style and length.

But there’s a problem with lithium-ion batteries: as they age and are charged, they develop dendrites. A research team from the University of Houston is trying to solve the dendrite problem by investigating how these structures grow on batteries. Dendrites are spiky structures that accumulate on the batteries’ anodes. These structures reduce the life of the batteries, hinder their ability to hold a charge and can short-circuit machines potentially causing safety hazards like battery fires.

“By understanding how dendrites grow on batteries, we can identify chemical and physical solutions to prevent the growth of dendrites, which is necessary to develop the next generation of batteries,” said Xiaonan Shan, assistant professor of electrical and computer engineering at UH’s Cullen College of Engineering.

Shan and his team have developed a “novel in-situ” 3D microscopy to image and study the localized electrochemical environments and understand where dendrites start forming in batteries. Using the 3D microscope, small cameras and other computer imaging technology, Shan and his team were able to geometrically map out how a battery initially develops dendrites.

The findings were recently published in the journal Advanced Energy Materials.

“This is significant because most battery researchers traditionally use electrochemical measurements to measure the entire surface or interior battery, so they don’t know what happens inside the battery,” said Shan, who is a corresponding author on the paper. Electrical and computer engineering graduate student Guangxia Feng is the lead author. Most battery companies focus on the materials part of developing batteries, so new materials emphasize performance, he added.

“With this process, manufacturers can theoretically make better performing batteries by focusing on the structural design of batteries that discourages the growth of dendrites,” Shan noted. “And in the next step, we will use this technique to design highly efficient Zn (zinc-carbon) batteries.”

Authors joining Shan and Feng on the paper are Jiaming Guo, Yaping Shi, Xiaoliang, Xu Yang and David Mayerich, all of the UH Department of Electrical and Computer Engineering; and Huajun Tian, Zho Li and Yang Yang, University of Central Florida.

Story Source:

Materials provided by University of Houston. Original written by Karn Dhingra. Note: Content may be edited for style and length.

Advances in quantum science have the potential to revolutionize the way we live. Quantum computers hold promise for solving problems that are intractable today, and we may one day use quantum networks as hackerproof information highways.

The realization of such forward-looking technologies hinges in large part on the qubit — the fundamental component of quantum systems. A major challenge of qubit research is designing them to be customizable, tailored to work with all kinds of sensing, communication and computational devices.

Scientists have taken a major step in the development of tailored qubits. In a paper published in the Journal of the American Chemical Society, the team, which includes researchers at MIT, the University of Chicago and Columbia University, demonstrates how a particular molecular family of qubits can be finely tuned over a broad spectrum, like turning a sensitive dial on a wideband radio.

The team also outlines the underlying design features that enable exquisite control over these quantum bits.

“This is a new platform for qubit design. We can use our predictable, controllable, tunable design strategy to create a new quantum system,” said Danna Freedman, MIT professor of chemistry and a co-author of the study. ?”We’ve demonstrated the broad range of tunability over which these design principles work.”

The work is partially supported by Q-NEXT, a U.S. Department of Energy (DOE) National Quantum Information Science Research Center led by Argonne National Laboratory.

The researchers’ work focuses on a specific group of molecules: those with a central chromium atom surrounded by four hydrocarbon molecules to form a pyramidlike structure.

The molecular qubit advantage

The qubit is the quantum equivalent of the traditional computing bit. Physically, it may take any of several forms, such as a specially prepared atom inside a crystal or an electrical circuit. It can also be a lab-made molecule.

One advantage of a molecular qubit is that, like a tiny 3D-printed gadget, it can be engineered from the bottom up, giving the scientist freedom to tune the qubit for different functions.

“We’re working to change the atomic structure through synthetic chemistry and then learning how those changes modify the physics of the qubit,” said Leah Weiss, a University of Chicago postdoctoral researcher and study co-author.

A molecular qubit’s information is stored in its spin, a property of atomic-level materials. Scientists engineer the spin by adjusting — tuning — the arrangement of the molecule’s electrons, its electronic structure. The information enters the qubit as particles of light, or photons, and is encoded in the qubit’s spin. The spin-encoded information is then translated again into photons, to be read out.

Different photon wavelengths are more suitable for different applications. One wavelength may work better for biosensing applications, another for quantum communication.

The ligand’s the thing

One of the molecular qubit’s key tuning dials is the ligand field strength, the strength of the bonds connecting the central metal atom to the surrounding hydrocarbons.

“The ligand is fundamentally everything. We can intentionally control the way in which the ligand environment influences the spin and rationally control where the emitted photons end up,” said Dan Laorenza, MIT graduate student and lead author of the paper.

Researchers demonstrated that they could exercise remarkably fine tuning over these bonds. Not only that, but they also showed that the ligand field strengths are adjustable over a relatively broad spectrum, while computational simulations performed by researchers at Columbia provided quantum mechanical insight into the ligands’ role in controlling the molecule’s electronic properties.

The light emitted by their chromium qubits spanned an impressive 100 nanometers.

“This is an unprecedented range of tunability for qubits targeting designer applications,” Freedman said.

“Just by keeping the central metal ion the same, which is doing the hard work of the quantum information processing, but tuning the surrounding environment through ligands, you can play around with the properties,” said University of Glasgow’s Sam Bayliss, who co-authored the study while a postdoctoral researcher at the University of Chicago. ?”That’s very hard to do with other systems, like solid-state systems, where you’re essentially fixed at whatever the elemental properties give you.”

A solid-state qubit is created by scooping out a tiny, atom-sized bit of matter from a crystal, and the resulting vacancy is where quantum information is stored and processed. While they have their advantages, solid-state qubits can’t be tuned with the same chemical precision, for example.

“With those, effectively, you get no tuning,” Freedman said. ?”You’re really going from zero to 100 there.”

Laying out the design rules

Approaching the molecule’s design by focusing on its electronic structure — the molecule’s energy levels — rather than its physical structure was key to the team’s discovery.

“Throwing the physical structure out the window and focusing entirely on the electronic structure, which is something that can be achieved across a range of molecular platforms, is really the key innovative detail,” Freedman said.

The researchers spell out the design criteria for building similar molecules in their paper, laying the groundwork for creating new tunable molecular qubits that can be designed toward a future application.

“Having demonstrated the accuracy of our computational methods on these chromium qubits, we can now use the same methods to simplify the screening process,” said Arailym Kairalapova, one of the Columbia researchers who performed the calculations.

“By bringing together the tools of chemistry and physics, it’s possible to start to understand the design rules that will guide the continued improvement of this class of qubits,” Weiss said.

One could custom-design qubits that attach to a biological system and use them for quantum biosensing. Or researchers could architect a qubit to be water-soluble so that it could detect signals in an aqueous environment.

“One of the terrific things about this platform is that, if the molecule doesn’t emit at a certain wavelength, it’s easy for us to go back in the lab, make a new material at a low cost, and see which one gives us the appropriate feature we want,” Laorenza said. ?”We can do this in a few days. It’s not something that takes a really intense, high amount of fabrication.”

The team attributes its success also to innovations in studies of light-matter interactions.

“A few years ago, this was just a dream — to have a set of molecular systems be a novel platform for quantum information science,” Bayliss said. ?”Seeing where we are now is really exciting.”

The team plans to explore different ligand environments to widen the range of photon emission.

“This is now a jumping off point that we hope allows many more chemists to be invited into this space, opening up the work to a much broader range of chemists who could contribute quite a bit to quantum information science,” Laorenza said.

This work was supported by the U.S. Department of Energy Office of Science National Quantum Information Science Research Centers.

Fast radio bursts are unpredictable, extremely short flashes of light from space. Astronomers have struggled to understand them ever since they were first discovered in 2007. So far, they have only ever been seen by radio telescopes.

Each flash lasts only thousandths of a second. Yet each one sends out as much energy as the Sun gives out in a day. Several hundred flashes go off every day, and they have been seen all over the sky. Most lie at huge distances from Earth, in galaxies billions of light years away.

In two papers published in parallel this week in the journals Nature and Nature Astronomy, an international team of astronomers present observations that take scientists a step closer to solving the mystery — while also raising new puzzles. The team is led jointly by Franz Kirsten (Chalmers, Sweden, and ASTRON, Netherlands) and Kenzie Nimmo (ASTRON and University of Amsterdam).

The scientists set out to make high-precision measurements of a repeating burst source discovered in January 2020 in the constellation of Ursa Major, the Great Bear.

“We wanted to look for clues to the bursts’ origins. Using many radio telescopes together, we knew we could pinpoint the source’s location in the sky with extreme precision. That gives the opportunity to see what the local neighbourhood of a fast radio burst looks like,” says Franz Kirsten.

To study the source at the highest possible resolution and sensitivity, the scientists combined measurements from telescopes in the European VLBI Network (EVN). By combining data from 12 dish antennas spread across half the globe, Sweden, Latvia, The Netherlands, Russia, Germany, Poland, Italy and China, they were able to find out exactly where in the sky they were coming from.

The EVN measurements were complemented with data from several other telescopes, among them the Karl G. Jansky Very Large Array (VLA) in New Mexico, USA.

Close but surprising location

When they analysed their measurements, the astronomers discovered that the repeated radio flashes were coming from somewhere no one had expected. They traced the bursts to the outskirts of the nearby spiral galaxy Messier 81 (M 81), about 12 million light years away. That makes this the closest ever detection of a source of fast radio bursts.

There was another surprise in store. The location matched exactly with a dense cluster of very old stars, known as a globular cluster.

“It’s amazing to find fast radio bursts from a globular cluster. This is a place in space where you only find old stars. Further out in the universe, fast radio bursts have been found in places where stars are much younger. This had to be something else,” says Kenzie Nimmo.

Many fast radio bursts have been found surrounded by young, massive stars, much bigger than the Sun. In those locations, star explosions are common and leave behind highly magnetised remnants.Scientists have come to believe that fast radio bursts can be created in objects known as magnetars. Magnetars are the extremely dense remnants of stars that have exploded. And they are the universe’s most powerful known magnets.

“We expect magnetars to be shiny and new, and definitely not surrounded by old stars. So if what we’re looking at here really is a magnetar, then it can’t have been formed from a young star exploding. There has to be another way,” says team member Jason Hessels, University of Amsterdam and ASTRON.

The scientists believe that the source of the radio flashes is something that has been predicted, but never seen before: a magnetar that formed when a white dwarf became massive enough to collapse under its own weight.

“Strange things happen in the multi-billion-year life of a tight cluster of stars. Here we think we’re seeing a star with an unusual story,” explains Franz Kirsten.

Given time, ordinary stars like the Sun grow old and transform into small, dense, bright objects called white dwarfs. Many stars in the cluster live together in binary systems. Of the tens of thousands of stars in the cluster, a few get close enough that one star collects material from the other.

That can lead to a scenario known as “accretion-induced collapse,” Kirsten explains.

“If one of the white dwarfs can catch enough extra mass from its companion, it can turn into an even denser star, known as a neutron star. That’s a rare occurrence, but in a cluster of ancient stars, it’s the simplest way of making fast radio bursts,” says team member Mohit Bhardwaj, McGill University, Canada.

Fastest ever

Looking for further clues by zooming into their data, the astronomers found another surprise. Some of the flashes were even shorter than they had expected.

“The flashes flickered in brightness within as little as a few tens of nanoseconds. That tells us that they must be coming from a tiny volume in space, smaller than a soccer pitch and perhaps only tens of metres across,” says Kenzie Nimmo.

Similarly lightning-fast signals have been seen from one of the sky’s most famous objects, the Crab pulsar. It is a tiny, dense, remnant of a supernova explosion that was seen from Earth in 1054 CE in the constellation of Taurus, the Bull. Both magnetars and pulsars are different kinds of neutron stars: super-dense objects with the mass of the Sun in a volume the size of a city, and with strong magnetic fields.

“Some of the signals we measured are short and extremely powerful, in just the same way as some signals from the Crab pulsar. That suggests that we are indeed seeing a magnetar, but in a place that magnetars haven’t been found before,” says Kenzie Nimmo.

Future observations of this system and others will help to tell whether the source really is an unusual magnetar, or something else, like an unusual pulsar or a black hole and a dense star in a close orbit.

“These fast radio bursts seem to be giving us new and unexpected insight into how stars live and die. If that’s true, they could, like supernovae, have things to tell us about stars and their lives across the whole universe,” says Franz Kirsten.